ZOJ 2795 Ambiguous permutations 水～

题目刚开始没看懂，看了别人博客里的解释才知道是咋回事。。。。。汗，还是挺简单的。。。

#include <cstring>#include <iostream>using namespace std;int arr[100002];int main(void) {  int n;  while (cin >> n && n) {    bool flag = true;    memset(arr, 0, sizeof(arr));    for (int i = 1; i <= n; i++) {      cin >> arr[i];    }    for (int j = 1; j <= n; j++) {      if (arr[arr[j]] != j) {        flag = false;        break;      }    }    if (flag)      cout << "ambiguous\n";    else      cout << "not ambiguous\n";  }  return 0;}