Replace a Text By Another Text in String (Algorithm 3.2)

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/**Bismillahir Rahmanir Rahim.**/

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

int l_T, l_P, l_Q, x, y, move, k;

int Index(char t[], char p[])
{
    int k=-1, r, s, max, l, m, cnt, i;
    s = strlen(t);
    r = strlen(p);
    max = s-r+1;
    for(i=0; i<max; i++)
    {
        if(t[i]==p[0])
        {
            for(l=1, cnt=1, m=i+1; l<r; l++, m++)
            {
                if(p[l]==t[m]) cnt++;
                else break;
            }
            if(cnt==r)
            {
                k = i;
                break;
            }
        }
    }
    return k;
}

char *REPLACE_1(char t[], char p[], char q[], int k)
{
    l_T = strlen(t);
    l_P = strlen(p);
    l_Q = strlen(q);
    move = l_Q-l_P;
    for(x=l_T-1; x>=k; x--)
        t[x+move] = t[x];
    t[l_T+move] = '\0';
    for(x=k, y=0; y<l_Q; x++,y++)
        t[x] = q[y];
    return t;

}
char *REPLACE_2(char t[], char p[], char q[], int k)
{
    l_T = strlen(t);
    l_P = strlen(p);
    l_Q = strlen(q);
    move = l_P-l_Q;
    for(x=k+move; x<l_T; x++)
        t[x-move] = t[x];
    t[l_T-move] = '\0';
    for(x=k, y=0; y<l_Q; x++,y++)
        t[x] = q[y];
    return t;

}

int main()
{
    char *T=malloc(sizeof(char)*5000);
    char  P[1000], Q[1000];
    printf("Please, Input Text.\n");
    gets(T);
    printf("Please, Input What You Want To Remove.\n");
    l_P = strlen(gets(P));
    printf("Please, Input What You Want To Replace on Remove.\n");
    l_Q = strlen(gets(Q));
    for(k=Index(T,P); k!=-1; )
    {
        if(l_P<l_Q) T = REPLACE_1(T,P,Q,k);
        else T = REPLACE_2(T,P,Q,k);
        k=Index(T,P);
    }
    printf("%s\n", T);
    free(T);
    return 0;
}