aoa

expt1
#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define len 100000
    double selectionsort(int a[],long int n)
    {
    long int i,j,pos;
    int min;
    clock_t t1,t2;
    double time_elapsed;
    t1=clock();
    for(i=0;i<n;i++)
    {
        min=a[i];
        pos=i;
        for(j=i+1;j<n;j++)
        {
        if(min>a[j])
        {
            min=a[j];
            pos=j;
        }
        }
        a[pos]=a[i];
        a[i]=min;
    }
    t2=clock();
    time_elapsed=(double)(t2-t1)/CLOCKS_PER_SEC;  //time elapsed for selection sort
    return time_elapsed;
     }

    double insertionsort(int a[],long int n)
    {
    long int i,j;int temp;
    clock_t t1,t2;
    double time_elapsed;
    t1=clock();
    for(j=1;j<n;j++)
    {
        i=j-1;
        temp=a[j];
        while(i>=0 && a[i]>temp)
        {
        a[i+1]=a[i];
        i--;
        }
        a[i+1]=temp;
    }
    t2=clock();
    time_elapsed=(double)(t2-t1)/CLOCKS_PER_SEC;  //time elapsed for insertion sort
    return time_elapsed;
     }
 void dataread(int a[])
     {
     long int i;
     FILE *fp;
     fp=fopen("data.txt","r");
     for(i=0;i<len;i++)
     {
         fscanf(fp,"%d",&a[i]);
     }
     fclose(fp);
     }

     int main(void)
     {
     int a[len],nextrand;
     long int i;
     FILE *fp;
     fp=fopen("data.txt","w");
     for(i=0;i<len;i++)
     {
         nextrand=rand()%100;
         fprintf(fp,"%d\n",nextrand);
     }
     fclose(fp);
     printf("\t\t  Insertion\t        Selection\n");
     for(i=10;i<=len;i=i*10)  //multiples of 10 number of integers starting from 10
     {
       printf("%ld integers",i);
       dataread(a);
       printf("\t%.9lf\t",insertionsort(a,i));
       printf("\t%.9lf",insertionsort(a,i));
       printf("\n");
    }
    return 0;
     }


expt2

#include <stdio.h>
#include <stdlib.h>
#include<time.h>
#define len 250000

    void merge(int a[],long int lb, long int m, long int ub)
    {
    int temp[len];
    long int i,j,k;
    i=lb;
    j = m+1;
    k = 0;
    while(i<=m && j<=ub)
     if (a[i]<a[j])
          temp[k++] = a[i++];
     else temp[k++] = a[j++];
    while (i<=m)
        temp[k++] = a[i++];
    while (j<=ub)
        temp[k++] = a[j++];
    k=0;
    for (i=lb; i<=ub; i++)
         a[i] = temp[k++];
    return;
    }

    void mergesort(int a[],long int lb,long int ub)
    {
    long int m;
    if (lb < ub)
    {
     m = (lb+ub)/2;
     mergesort(a, lb, m);
     mergesort(a, m+1, ub);
     merge(a, lb, m, ub);
     }
     return;
    }

     long int partition(int a[], long int lb, long int ub)
     {
     long int down, up;
     int val, temp;
     val = a[lb];
     down = lb+1;
     up = ub;
     while(down<=up)
     {
      while (down<=up && a[down]<=val)
        down = down + 1;
      while (a[up]>val)
        up = up - 1;
      if (down < up)
         {
          temp = a[down];
          a[down] = a[up];
          a[up] = temp;
         }
     }
     a[lb] = a[up];
     a[up] = val;
     return up;
     }
    void quicksort(int a[],long int lb, long int ub)
    {
    long int p;
    if (lb<ub)
    {
     p = partition(a, lb, ub);
     quicksort(a, lb, p-1);
     quicksort(a, p+1, ub);
    }
    return;
     }

     void dataread(int a[])
     {
     FILE *fp;
     long int i;
     fp=fopen("data.txt","r");
     for(i=0;i<len;i++)
     {
         fscanf(fp,"%d",&a[i]);
     }
     fclose(fp);
     }

     int main(void)
     {
     int a[len],nextrand;
     long int i;
     double time_elapsed,time;
     clock_t t1,t2,t3,t4;
     FILE *fp;
     fp=fopen("data.txt","w");
     for(i=0;i<len;i++)
     {
         nextrand = rand()%100;
         fprintf(fp,"%d\n",nextrand);
     }
     fclose(fp);
     printf("\t\t  Merge\t\t        Quick\n");
     for(i=10;i<=len;i=i*10)  //multiples of 10 number of integers starting from 10
     {
        printf("%ld integers",i);
        dataread(a);
        t1 = clock();
        mergesort(a,0,i);
        t2 = clock();
        time_elapsed = (double)(t2-t1)/CLOCKS_PER_SEC;
        printf("\t%lf\t",time_elapsed);
        quicksort(a,0,i);
        quicksort(a,0,i);
        t3 = clock();
        mergesort(a,0,i);
        t4 = clock();
        time = (double)(t4-t3)/CLOCKS_PER_SEC;
        printf("\t%lf",time);
        printf("\n");
     }
     return 0;
     }


expt 3

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>

void getminmax(int a[],int lb,int ub,int*fmin,int*fmax)
{
 int m,hmin,hmax,gmin,gmax;
 if(ub==lb)
 {
  *fmin = *fmax = a[ub];
  return;
 }
 if(ub==lb+1)
 {
  if(a[ub]<=a[lb])
  {
   *fmin=a[ub];
   *fmax=a[lb];
   return;
  }
  else
  {
   *fmin=a[lb];
   *fmax=a[ub];
   return;
  }
 }
 m=(lb+ub)/2;
 getminmax(a,lb,m,&hmin,&hmax);
 getminmax(a,m+1,ub,&gmin,&gmax);
 if(hmin <= gmin)
      *fmin = hmin;
 else *fmin = gmin;
 if(hmax > gmax)
      *fmax = hmax;
 else *fmax = gmax;
 return;
}


void main(void)
{
 int n,i,a[30000],nextrand,min,max;
 FILE *fp;
 min=0;
 max=0;
 printf("Enter number of integers: ");
 scanf("%d",&n);
 fp=fopen("data.txt","w");
 for(i=0;i<n;i++)
 {
  nextrand=rand()%100;
  fprintf(fp,"%d ",nextrand);
 }
 fclose(fp);
 fp=fopen("data.txt","r");
 for(i=0;i<n;i++)
 {
  fscanf(fp,"%d ",&a[i]);
  printf("%d ",a[i]);
 }
 fclose(fp);
 getminmax(a,0,n-1,&min,&max);
 printf("\n\nMaximum = %d",max);
 printf("\nMinimum = %d\n",min);
 getch();
}


expt 4

#include<stdio.h>

void shiftup(int a[][512],int n,int lb,int ub)
{
    int i,j;  //function to circular shift
    j=a[lb][n];
    for(i=lb;i<ub;i++)
        a[i][n]=a[i+1][n];
    a[ub][n]=j;
}
void shiftdown(int a[][512],int n,int lb,int ub)
{
    int i,j; //function for reverse circular shift
    j=a[ub][n];
    for(i=ub;i>lb;i--)
        a[i][n]=a[i-1][n];
    a[lb][n]=j;
}
void compute(int a[][512],int lb,int ub)
{
    int m,i,j,k=(ub-lb)/2,d;
    if(ub-lb==1)
    {
        a[ub][0]=lb+1;  //only two teams
        a[lb][0]=ub+1;
        return;
    }
    m=(lb+ub)/2;     // divide stage
    compute(a,lb,m);
    compute(a,m+1,ub);

    j=m+2;
    for(i=lb;i<=m;i++)    //creating a new upper column after all dealing with all the sub parts.
    {
        a[i][k]=j;
        j++;
    }
    for(i=k+1;i<ub;i++)  // circular shifting the columns
    {
        for(j=lb;j<=m;j++)
            a[j][i]=a[j][i-1];
        shiftup(a,i,lb,m);
    }

    j=lb+1;
    for(i=m+1;i<=ub;i++)   //creating a new lower column after all dealing with all the sub parts.
    {
        a[i][k]=j;
        j++;
    }
    for(i=k+1;i<ub;i++) //reverse circular shifting the columns
    {
        for(j=m+1;j<=ub;j++)
            a[j][i]=a[j][i-1];
        shiftdown(a,i,m+1,ub);
    }
}

void main()
{
    int i,j,n,a[512][512];
    printf("Enter the number of players: ");
    scanf("%d",&n);
    compute(a,0,n-1);
    printf("The tournament schedule is:\n\nDays:\t");
        for(i=1;i<n;i++)
            printf("D%.2d ",i);   //displaying the days row
        printf("\n");
        printf("Players:\n");
        for(i=0;i<n;i++)
        {
            printf("%2d\t",i+1);   //displaying team number
            for(j=0;j<n-1;j++)
                printf("%3d ",a[i][j]);    //displaying the required schedule
            printf("\n");
        }
}


expt 5

#include<stdio.h>
#include<conio.h>

typedef struct
{
 float p[20],w[20];
}knapsack;

void bubblesort(knapsack *k, int n, float a[])
{
 int i, j;
 float temp;
 for (i=0; i<n; i++)
    {
     a[i] = k->p[i]/k->w[i];
    }
 for (i=0; i<n-1; i++)
    for (j=0; j<n-i-1; j++)
        if (a[j] < a[j+1])
        {
         temp = a[j];
         a[j] = a[j+1];
         a[j+1] = temp;
         temp = k->p[j];
         k->p[j] = k->p[j+1];
         k->p[j+1] = temp;
         temp = k->w[j];
         k->w[j] = k->w[j+1];
         k->w[j+1] = temp;
        }
 return;
}

void fknap(knapsack k, int n, int M)
{
 int i;
 float cp=0,cw=0,a[20];
 bubblesort(&k,n,a);
 printf("The sorted list is:\n");
 for (i=0; i<n; i++)
    {
     printf("\n%.0f | ",k.p[i]);
     printf("%.0f | ",k.w[i]);
     printf("%f ",a[i]);
    }
 printf("\n");
 for (i=0; i<n; i++)
    if ((cw+k.w[i]) < M)
        {
         cp = cp+k.p[i];
         cw = cw+k.w[i];
        }
    else
        {
         cp = cp+((k.p[i]/k.w[i])*(M-cw));
         cw = M;
         break;
        }
 printf("\nProfit = %f\n",cp);
 printf("Weight = %f\n",cw);
 return;
}

void knap0_1(knapsack k, int n, int M)
{
 int i,cp=0,cw=0;
 float a[20];
 bubblesort(&k,n,a);
 printf("The sorted list is:\n");
 for (i=0; i<n; i++)
    {
     printf("\n%.0f | ",k.p[i]);
     printf("%.0f | ",k.w[i]);
     printf("%f ",a[i]);
    }
 printf("\n");
 for (i=0; i<n; i++)
    {
     if ((cw+k.w[i]) <= M)
        {
         cp = cp+k.p[i];
         cw = cw+k.w[i];
        }
     if (cw == M)
         break;
    }
 printf("\nProfit = %d\n",cp);
 printf("Weight = %d\n",cw);
 return;
}

void main(void)
{
 int i,n,M,ch;
 knapsack k;
 printf("Enter no. of items: ");
 scanf("%d",&n);
 printf("Enter the profits of %d items: ",n);
 for (i=0; i<n; i++)
    scanf("%f", &k.p[i]);
 printf("Enter the weights of %d items: ",n);
 for (i=0; i<n; i++)
    scanf("%f", &k.w[i]);
 printf("Enter maximum capacity of the sack: ");
 scanf("%d",&M);
 do
 {
  printf("\nEnter choice from the following\n1. Fractional Knapsack\n2. 0/1 Knapsack\n3. Exit\n\n");
  scanf("%d",&ch);
  switch(ch)
  {
   case 1   : printf("Fractional Knapsack's result:\n");
              fknap(k,n,M);
              break;
   case 2   : printf("0/1 Knapsack's result:\n");
              knap0_1(k,n,M);
              break;
   case 3   : printf("THANK YOU\n");
              break;
   default  : printf("INVALID CHOICE\n");
              break;
  }
 }while(ch>=1&&ch<=2);
 getch();
}

expt 6
#include <stdio.h>
#include <stdlib.h>
#define INFY 32000

void input_weight_matrix(int v[][50],int n,int e)
{
    int x,y,cost;
    for(x=1;x<=n;x++)
        for(y=1;y<=n;y++)
            v[x][y]=INFY;
    while(n>0)
        v[n][n--]=0;
    while(e>0)
    {
        printf("Enter Edge as\"u_v_cost\":");
        scanf("%d %d %d",&x,&y,&cost);
        v[x][y]=cost;
        v[y][x]=cost;
        e--;
    }
}

void add_edge(int mcst[][50],int x,int y,int w)
{
    mcst[x][y]=w;
    mcst[y][x]=w;
}

void add(int a[],int *n,int x)
{
    a[(*n)]=x;
    (*n)++;
}

int extract(int a[],int *n,int b)
{
    int r,i;
    for(i=0;a[i]!=b;i++);
    r=a[i];
    (*n)--;
    for(i;i<(*n);i++)
        a[i]=a[i+1];
    return r;
}

void primms_mcst(int w[][50],int mcst[][50],int n,int s)
{
    int v[50],uv[50],vn=0,uvn=0,i=1,j=1,x,y,mw=INFY;
    add(v,&vn,s);
    while(i<=n)
    {
        if(i!=s)
        add(uv,&uvn,i);
        i++;
    }
    while(uvn>0)
    {
        mw=INFY;
        for(i=0;i<vn;i++)
            for(j=0;j<uvn;j++)
                {
                if((w[(v[i])][(uv[j])])<mw)
                {
                    x=v[i];
                    y=uv[j];
                    mw=w[v[i]][uv[j]];
                }
                }
        add_edge(mcst,x,y,mw);
        v[vn++]=extract(uv,&uvn,y);
    }
}

void display_mat(int a[][50],int n)
{
    int i,j;
    for(i=1;i<=n;i++)
    {
        printf("\n");
        for(j=1;j<=n;j++)
            if(a[i][j]==INFY)
            printf(" Inf");
            else printf("%4d",a[i][j]);
    }
}

void print_mcst(int mcst[][50],int n)
{
    int cost=0,i,j;
    for(i=1;i<=n;i++)
        for(j=i;j<=n;j++)
            {
            if(mcst[i][j]==0)
                continue;
            printf("(%d,%d),",i,j);
            cost+=mcst[i][j];
            }
    printf("\nMinimum Cost = %d",cost);
}

int main()
{
    int w[50][50],n,mcst[50][50],e,s;
    printf("Enter the No.of vertices and edges: ");
    scanf("%d %d",&n,&e);
    input_weight_matrix(w,n,e);
    display_mat(w,n);
    printf("\nEnter the starting node: ");
    scanf("%d",&s);
    primms_mcst(w,mcst,n,s);
    printf("\nPrims MCST_MAT:\n");
    display_mat(mcst,n);
    printf("\nThat is RESULT: ");
    print_mcst(mcst,n);
    return 0;
}


expt 7

#include<stdio.h>

void init(int COST[][50],int D[][50],int n)
{
 int i,j,c;
 for (i=0; i<n; i++)
     for (j=0; j<n; j++)
     {
         COST[i][j] = 999;
         D[i][j] = -1;
     }
 c=n-1;
 while(c>=0)
 {
  COST[c][c--]=0;
 }
}

void readEdges(int COST[][50],int D[][50],int e)
{
 int u,v,c;
 while (e!=0)
 {
  printf("Enter edge as \"u_v_cost\": ");
  scanf("%d %d %d",&u,&v,&c);
  COST[u-1][v-1]=c;
  D[u-1][v-1]=u;
  e--;
 }
}

void displayMat(int Mat[][50], int n)
{
 int i,j;
 for (i=0;i<n;i++)
 {
     for (j=0;j<n;j++)
        printf("%3d ", Mat[i][j]);
     printf("\n");
 }
}

void apsp(int COST[][50],int A[][50],int D[][50],int n)
{
 int i,j,k,t;
 for (i=0; i<n; i++)
     for (j=0;j<n;j++)
         A[i][j]=COST[i][j];
 for (k=0;k<n;k++)
     for (i=0;i<n;i++)
        for(j=0;j<n;j++)
        {
           t = A[i][k]+A[k][j];
           if (A[i][j]>t)
           {
               A[i][j] = t;
               D[i][j] = k+1;
           }
        }
}

void pathfinding(int COST[][50],int D[][50],int s, int d)
{
 int i=1,j,FINAL[50];
 j=d;
 FINAL[0]=d;
 while(D[s-1][d-1]!= -1)
 {
  FINAL[i++]=D[s-1][d-1];
  if (COST[d-1][j-1]==999)
      {
          s = D[s-1][d-1];
          continue;
      }
  d = D[s-1][d-1];
 }
 printf("\nPath: ");
 for(j=i-1;j>0;j--)
    printf("%d-",FINAL[j]);
 printf("%d",FINAL[0]);
}

int main(void)
{
 int A[50][50],COST[50][50],D[50][50],n,e,s,q;
 printf("Enter no. of vertices: ");
 scanf("%d",&n);
 printf("Enter no. of edges: ");
 scanf("%d",&e);
 init(COST,D,n);
 readEdges(COST,D,e);
 printf("\nWeight Mat:\n");
 displayMat(COST,n);
 printf("Decision Mat initially:\n");
 displayMat(D,n);
 apsp(COST,A,D,n);
 printf("\nFinal Length Mat:\n");
 displayMat(A,n);
 printf("Final Decision Mat:\n");
 displayMat(D,n);
 printf("\nEnter starting and ending nodes: ");
 scanf("%d%d",&s,&q);
 printf("Minimum Length between %d and %d = %d",s,q,A[s-1][q-1]);
 pathfinding(COST,D,s,q);
 return 0;
}


expt 8

#include<stdio.h>

typedef struct
{
    int n[50];
    int v;
    int min;
}PS;

PS tsp(int s,PS list,int D[][50],int m)
{
   int i,j;
   PS nlist,npath,nmin;
   if(list.v==0)
   {
       nmin.min=D[s][1];
       nmin.n[m-1]=s;
       nmin.v=m;
       return nmin;
   }
   for(i=0;i<list.v;i++)
   {
      nlist.v=0;
      for(j=0;j<list.v;j++)
         if(i!=j)
           nlist.n[nlist.v++]=list.n[j];
      npath=tsp(list.n[i],nlist,D,m);
      npath.min=D[s][list.n[i]]+npath.min;
      npath.n[m-list.v-1]=s;
      if(i==0)
          nmin=npath;
      else if(npath.min<nmin.min)
               nmin=npath;
   }
   return nmin;
}

void display(PS path)
{
  int i;
  printf("\n\nThe minimum cost is: %d\n",path.min);
  printf("\n\nThe path is...\n");
  for(i=0;i<path.v;i++)
      printf("%d--",path.n[i]);
  printf("%d",path.n[0]);
}

int main()
{
   int i,j,D[50][50],m;
   PS graph,path;
   printf("Enter the number of nodes: ");
   scanf("%d",&m);
   for(i=1;i<=m;i++)
   {
       for(j=1;j<=m;j++)
          if(i==j)
             D[j][j]=0;
       else
       {
         printf("Enter distance from node %d to %d: ",i,j);
         scanf("%d",&D[i][j]);
       }
       if(i>1)
          graph.n[i-2]=i;
   }
   graph.v=m-1;
   path=tsp(1,graph,D,m);
   display(path);
   return 0;
}


expt 9


#include<stdio.h>
#include<conio.h>
#include<math.h>

void display(int x[],int n)
{
 int i,j;
 for (i=0; i<n; i++)
 {
    for (j=0; j<n; j++)
       if(x[i]==j)
        printf("Q ");
       else printf("# ");
   printf("\n");
 }
 printf("\n\n");
}

void nqueens(int x[],int r,int n)
{
 int c;
 for(c=0;c<n; c++)
 {
   if(place(x,r,c)==1)
   {
     x[r]=c;
     if(r==n-1)
     display(x,n);
     else nqueens(x,r+1,n);
   }
 }
}

int place(int x[],int r,int c)
{
  int j;
  for(j=0; j<r; j++)
     if(x[j]==c || abs(x[j]-c)==abs(j-r))
    return 0;
  return 1;
}

int main()
{
 int x[20],n;
 printf("Enter no of queens: ");
 scanf("%d",&n);
 nqueens(x,0,n);
 getch();
 return 0;
}


expt 10

#include<stdio.h>
#include<conio.h>

void display(int x[], int n)
{
 int i;
 for (i=0; i<n; i++)
     printf("%d ",x[i]);
 printf("\n");
}

void sumofsub(int w[],int x[],int M,int n,int s,int k,int r)
{
 int i;
 for (i=k; i<n; i++)
    x[i]=0;
 x[k]=1;
 if(s+w[k]==M)
     display(x,n);
 else if(s+w[k]+w[k+1]<=M)
        sumofsub(w,x,M,n,s+w[k],k+1,r-w[k]);
 if(s+r-w[k]>=M && s+w[k+1]<=M)
 {
   x[k]=0;
   sumofsub(w,x,M,n,s,k+1,r-w[k]);
 }
}

int main()
{
 int i,r=0;
 int w[20],n,M,x[20];
 printf("Enter no of weights: ");
 scanf("%d",&n);
 printf ("Enter the weights: ");
 for(i=0; i<n; i++)
 {
   scanf("%d",&w[i]);
   r=r+w[i];
 }
 printf("Enter required sum: ");
 scanf("%d",&M);
 printf("Selected List is:\n");
 sumofsub(w,x,M,n,0,0,r);
 return 0;
}

graph color

#include<conio.h>
#include<stdio.h>
#include<math.h>
int n,m,x[20]={0},ct=0,adj[10][10];
void nextval(int k)
{
 int j=1;
 x[k]=(x[k]+1)%(m+1);
 if(x[k]==0)
  return;
 while(j<k)
 {
  if(adj[j][k]==1 && x[j]==x[k])
   {
    x[k]=(x[k]+1)%(m+1);
    if(x[k]==0)
     return;
     j=1;

   }
  else j++;
  }
   return;
}
void dis()
{
 int i;
 ct=ct+1;
 printf("soluition=%d\n",ct);
 for(i=1;i<=n;i++)
  printf("%d ",x[i]);
 printf("\n");
 }

void colorg(int k)
{
 int i;
 for(i=1;i<=n;i++)
 {
 nextval(k);
 if(x[k]==0)
  return;
  if(k==n)
  {
   dis();
   }
  else colorg(k+1);
 }
}


void main()
{
 int i,j;
 clrscr();
 printf("Enter no of nodes\n");
 scanf("%d",&n);
 printf("Enter no of colors\n");
 scanf("%d",&m);
 for(i=1;i<=n;i++)
  for(j=1;j<=n;j++)
   scanf("%d",&adj[i][j]);

 colorg(1);
 getch();
}


lcs and clcs

#include<stdio.h>
#include<string.h>

int i,j,m,n,a,L[20][20];
char x[15],y[15],D[20][20];

void print_lcs(int i,int j)
{
    if(i==0 || j==0)
        return;
    if(D[i][j]=='d')
    {
        print_lcs(i-1,j-1);
        printf(" %c",x[i-1]);
    }
    else if(D[i][j]=='u')
        print_lcs(i-1,j);
    else
        print_lcs(i,j-1);
}

void lcs(void)
{
    m=strlen(x);
    n=strlen(y);
    for(i=0; i<=m; i++)
        L[i][0]=0;
    printf("\n\n");
    for(i=0; i<=n; i++)
    {
        printf("0 \t");
        L[0][i]=0;
    }
    printf("\n");
    for(i=1; i<=m ;i++)
    {
        printf("0 \t");
        for(j=1; j<=n; j++)
        {
            if(x[i-1]==y[j-1])
            {
                L[i][j]=L[i-1][j-1]+1;
                D[i][j]='d';
                printf("%d D\t",L[i][j]);
            }
            else if(L[i-1][j] > L[i][j-1])
            {
                L[i][j] = L[i-1][j];
                D[i][j] = 'u';
                printf("%d U\t",L[i][j]);
            }
            else
            {
                L[i][j]=L[i][j-1];
                D[i][j]='l';
                printf("%d L\t",L[i][j]);
            }
        }
        printf("\n");
    }
    printf("\nLongest common subsequence is :");
    print_lcs(m,n);
    printf("\n");
    printf("The length of Subsequence is: %d",L[m][n]);
}

void main()
{
    printf("Enter 1st sequence : ");
    scanf("%s",x);
    printf("Enter 2nd sequence : ");
    scanf("%s",y);
    lcs();
    printf("\n");
    getch();
}

naive pattern

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

int brute_force(char x[],char y[])
{
 int i,j,n,m;
 n = strlen(x);
 m = strlen(y);
 for (i=0; i<n-m; i++)
    {
     j = 0;
     while(j<m && x[i+j]==y[j])
        j = j+1;
     if (j==m)
        return i;    //starting index of the text part where pattern is matched
    }
 return -1;          //pattern not matched in the entire text
}

int main()
{
 char t[20],p[10];
 int result;
 printf("Enter the text: ");
 scanf("%s",t);
 printf("Enter the pattern needed to be found: ");
 scanf("%s",p);
 result = brute_force(t,p);
 if(result != -1)
      printf("\nThe pattern is matched in the text from: %d index of the text.",result);
 else printf("\nThe pattern didn't matched!!!");
 printf("\n");
 getch();
}

kmp and cmkp

#include<conio.h>
#include<stdio.h>
#include<string.h>
int f[30];
void kmpfail(char p[],int m)
{
 int i=1,j=0;
 f[0]=0;
 while(i<m)
 {
  if(p[j]==p[i])
   {
    f[i]=j+1;
    i=i+1,j=j+1;
   }
  else if(j>0)
     j=f[j-1];
       else
    {
     f[i]=0;
     i=i+1;
    }
  }
 return;
}
int kmp(char t[],char p[], int n,int m)
{
 int i=0,j=0;
 while(i<n)
 {
  if(p[j]==t[i])
    if(j==m-1)
     return i-m+1;
    else i=i+1,j=j+1;
  else if(j>0)
    j=f[j-1];
       else i=i+1;
  }
 return -1;
}
void main()
{
 int n,m;
 char t[30],p[10];
 clrscr();
 printf("Enter text\n");
 gets(t);
  n=strlen(t);
 printf("Enter pattern\n");
 gets(p);
 m=strlen(p);
 kmpfail(p,m);
 if(kmp(t,p,n,m)!=-1)
  printf("pattern is present at %d",kmp(t,p,n,m));
 else printf("pattern not found");
 getch();
}