Anonymous

#include <stdio.h>#include <stdlib.h>int main() {    FILE *fin, *fout;    fin = fopen("s3.in", "r");    fout = fopen("s3.out", "w");        int list[10000] = { 0 }; // x must be friends with list[x]    int nstudents;        fscanf(fin, "%d", &nstudents);        for (; nstudents > 0; nstudents--) {        int x, y;        fscanf(fin, "%d %d", &x, &y);        list[x] = y;    }        while (1) {          int from, to;          fscanf(fin, "%d %d", &from, &to);                    if (from == 0 && to == 0)             break;                    int counter = 0, start = from, counting = 1;          printf("%d %d\n", from, to);                    while (1) {              // printf("%d is friends with %d\n", from, list[from]);              from = list[from];                            if (from == to)                 counting = 0;                            if (from == start) {                 if (counting == 0)                    fprintf(fout, "Yes %d\n", counter);                 else                     fprintf(fout, "No\n");                 break;              }                            if (!list[from]) {                 fprintf(fout, "No\n");                 break;              }                            if (counting)                 counter++;                        }              }        return 0;}