perm

#include "cranium.h"

int int_limit(int floor, int celing, char message[])
{
    int input;
    printf("%s\n? ", message);
    do
    {
        scanf_s("%d", &input);
        if (input >= floor&&input <= celing) break;
        else printf("Invalid input. Please enter a %d < number < %d.\n?", floor, celing);
    } while (YES);
    return input;
}

int factorial(int num)
{
    if (num == 1) return YES;
    else return num*factorial(num - 1);
}

int countComb(int N, int R)
{
    if (N == R) return YES;
    else return factorial(N) / (factorial(R)*factorial(N - R));
}

int countPerm(int N, int R)
{
    if (N == R) return YES;
    else return factorial(N) / factorial(N - R);
}

void swapElement(char *x, char *y)
{
    char temp;
    temp = *x;
    *x = *y;
    *y = temp;
}

int printNew(char base[], char input[])
{
    int similar = strlen(base);
    for (int i = 0; (unsigned)i < strlen(base); i++)
        if (base[i] == input[i]) similar--;
    if (similar==0) return NO;
    else return YES;
}


void list_permute(char *input, char *output, int startindex, int endindex, int setsize)
{
    int i; char temp[MAXARRAY] = { '0' };
    if (startindex == endindex)
    {
        strncpy(temp, input, setsize);
        if (printNew(output, temp))
        {
            printf("%s\n", temp);
            strcpy(output, temp);
        }
    }
    else
    {
        for (i = startindex; i <= endindex; i++)
        {
            swapElement((input + startindex), (input + i));
            list_permute(input, output, startindex + 1, endindex, setsize);
            swapElement((input + startindex), (input + i));
        }
    }
}


void list_comb(char input[], int n, int r)
{
    char data[MAXARRAY];
    comb_switch(input, data, 0, n - 1, 0, r);
}

void comb_switch(char input[], char data[], int start, int end, int index, int r)
{
    if (index == r)
    {
        for (int j = 0; j<r; j++)
            printf("%c", data[j]);
        printf("\n");
        return;
    }
    for (int i = start; i <= end && end - i + 1 >= r - index; i++)
    {
        data[index] = input[i];
        comb_switch(input, data, i + 1, end, index + 1, r);
    }
}



void list_lexi(char *input, char *output, int startindex, int endindex, int setsize)
{
    int i;
    char temp[MAXARRAY] = {'0'};
    if (startindex == endindex)
    {
        strncpy(temp, input, setsize);
        if (printNew(output, temp))
        {
            if(lexi(temp, setsize)) printf("%s\n", temp);
            strcpy(output, temp);
        }
    }
    else
    {
        for (i = startindex; i <= endindex; i++)
        {
            swapElement((input + startindex), (input + i));
            list_lexi(input, output, startindex + 1, endindex, setsize);
            swapElement((input + startindex), (input + i));
        }
    }
}

int lexi(char input[], int length)
{
    int base, compare, pass;
    for (int i = 0; i<length; i++)
    {
        if (i + 1 == length)
        {
            break; return pass;
        }
        else
        {
            base = input[i];
            compare = input[i + 1];
        }
        if (base <= compare) pass = YES;
        else
        {
            pass = NO;
            break;
        }
    }
    return pass;
}