func_code_string: #include <bits/stdc++.h>   int main() {     int n;     scanf( %d , &n);     int a[200001];     int i;     for (i = 0; i < n; i++) {       scanf( %d , &a[i]);     }     long long buy = a[n - 1];     int pre = a[n - 1];     for (i = n - 2; i >= 0; i--) {       if (a[i] >= pre - 1) {         if (pre - 1 == 0)           break;         else           buy += pre - 1;         pre--;       } else {         buy += a[i];         pre = a[i];       }     }     printf( %lld n , buy);     return 0;   }   