#include <stdio.h>
int main(int argc, char *argv[]){ int n,b,i,m,flag=0,a[20]; while(scanf("%d",&n)!=EOF){ for(i=0;i<n;i++){ scanf("%d",&a[i]); } scanf("%d",&m); for(i=0;i<n;i++){ if(a[i]==m){ b=i; flag=1; break; } } if(flag==1){ printf("%d\n",b); } else{ printf("No\n"); } flag=0; } return 0;}原文：https://www.cnblogs.com/ars134419622/p/9937366.html