func_code_string: #include <bits/stdc++.h>   using namespace std;   int n;   int a[222222];   set<int> s;   int main() {     scanf( %d , &n);     for (int i = 1; i <= n; i++) {       s.insert(i);     }     for (int i = 1; i <= n; i++) {       scanf( %d , &a[i]);       if (a[i] != 0) {         s.erase(a[i]);       }     }     int idx = n;     int iidx = 0;     int iiidx = -1;     for (auto &x : s) {       while (a[idx] != 0) {         idx--;       }       a[idx] = x;       iidx = idx;       if (iiidx == -1) {         iiidx = idx;       }     }     for (int i = 1; i <= n; i++) {       if (a[i] == i) {         if (i == iidx) {           a[i] = a[iiidx];           a[iiidx] = i;         } else {           a[i] = a[iidx];           a[iidx] = i;         }         break;       }     }     for (int i = 1; i <= n; i++) {       printf( %d  , a[i]);     }     return 0;   }   