Dijkstra

#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <string>
#include <cstring>
#include <algorithm>
#include <fstream>
#include <sstream>
#include <queue>
#include <stack>
#define INP "input.INP"
#define OUT "output.OUT"
using namespace std;

typedef int item;
typedef struct GRAPH
{
    char *name; // ten cac dinh
    item **G;   // ma tran trong so
    int n;      // so phan tu cua do thi
} Graph;

void input_file();// lay du lieu tu file
void input_B_E(int &a, int &b); //nhap vao dinh dau va cuoi
void output(int a, int b);//Xuat ket qua tu file ra
void Dijkstra(int a, int b);//thuat toan Dijkstra
void Menu(int &select);
item tongthiethai(); //tong quang duong di cua moi dinh (thay the cho vo cung trong ma tran trong so)

Graph Gr;
int *Len;//Gia tri nho nhat tu a -> i. Len1 danh dau do dai.
int *S;//Danh dau dinh thuoc danh sach dac biet
int *P;//truy vet

int main()
{
    Graph Gr;
    input_file();
    int a, b, *P, i, select = 1;
    while (select)
    {
        cout<<endl<<"-----Thuat toan Dijkstra-----"<<endl;
        input_B_E(a, b);
        Dijkstra(a, b);
        output(a, b);
        Menu(select);
        if (!select) break;
    }
    return 0;
}

void input_file()   // nhap ma tran ke tu file
{
    ifstream inp(INP);
    if (inp == NULL)
    {
        cout<<"No found file input";
        return;
    }
    inp >> Gr.n ;

    Gr.name = new char [Gr.n];
    for (int i=0; i<Gr.n; i++)
        inp >> Gr.name[i];
    Gr.G = new int *[Gr.n];
    Len = new int [Gr.n];
    S = new int [Gr.n];
    P = new int [Gr.n];

    for (int i=0; i<Gr.n; i++)
    {
        Gr.G[i] = new int [Gr.n];
        for (int j=0; j<Gr.n; j++)
            inp >> Gr.G[i][j];
    }
    inp.close();
}

void input_B_E(int &a, int &b)
{
    a = b = 0;
    cout<<endl<<"Cac dinh danh so tu 1 den "<<Gr.n<<".Hoac tu "<<Gr.name[0]<<" den "<<Gr.name[Gr.n-1]<<endl;
    cout<<"Nhap dinh bat dau : ";
    while (a<1 || a> Gr.n)
    {
        cin>>a;
        if (a<1 || a> Gr.n)
            cout<<"Khong hop le ! \nNhap lai dinh bat dau : ";
    }

    cout<<"Nhap dinh ket thuc : ";
    while (b<1 || b> Gr.n)
    {
        cin>>b;
        if (b<1 || b> Gr.n)
            cout<<"Khong hop le ! \nNhap lai dinh ket thuc : ";
    }
    a -- ;
    b -- ;
}

void output(int a, int b)
{
    cout<<endl<<"Do dai ngan nhat cua duong di tu "<<a+1<<"("<<Gr.name[a]<<")"
        <<" den "<<b+1<<"("<<Gr.name[b]<<")"<<" la "<<Len[b]<<endl;
    cout<<"Qua trinh duong di: ";
    int i = b;
    char *s, *temp;
    s = new char [Gr.n*10];
    temp = new char [10];
    sprintf(s,"%d",i+1);
    while (i != a)
    {
        sprintf(temp,"%s"," --> ");
        strcpy(s,strcat(temp,s));
        sprintf(temp,"%d",P[i] +1);
        strcpy(s,strcat(temp,s));
        i = P[i];
    }
    cout<<s<<endl;
}

//tong quang duong di cua moi dinh (thay the cho vo cung trong ma tran trong so)
item tongthiethai()
{
    item sum = 0;
    for (int i=0; i<Gr.n; i++)
        for (int j=0; j<Gr.n; j++)
            sum += Gr.G[i][j];
    return sum;
}

void Menu(int &select)
{
    cout<<"Tiep tuc (1/0) ?";
    cin >> select;
}

void Dijkstra(int a, int b)     // thuat toan Dijkstra
{
    int max = tongthiethai();
    fill (Len,Len+Gr.n,max); //Gan duong di ban dau = vo cung
    fill (P,P+Gr.n,a);
    fill (S,S+Gr.n,0); //Danh sach dac biet
    Len[a] = 0;     // khoi tao do dai tu a->a = 0
    int i = a;

    //while S<>V
    for (int k=0; k<Gr.n; k++)
    {
        //tim do dai ngan nhat trong cac dinh
        for (i=0; i<Gr.n; i++) // tim v thuoc (V-S) va Len[v] < vo cung
            if (!S[i] && Len[i] != max)
                break;
        for (int j = i+1 ; j<Gr.n; j++) // tim dinh co Len min
            if (!S[j] && Len[j] < Len[i])
                i = j;
        S[i] = 1;   // dua dinh i vao S

        //--------Tinh do dai tu dinh dang xet toi cac dinh tiep
        for (int j = 0; j<Gr.n; j++) //thay doi do dai neu co
        {
            if (!S[j] && Gr.G[i][j])
                if (Len[i] + Gr.G[i][j] < Len[j])
                {
                    Len[j] = Len[i] + Gr.G[i][j];
                    P[j] = i; //truy vet
                }
        }
    }
}