# Could anyone help me? I'm stuck on January 2020 USACO Bronze Problem 2

Somehow, 8/10 tests are good and seem to work, while for other 2, the answers are incorrect. Could anyone help and tell my what is wrong with my code? It’s strange because I tried all possible examples within the boundary of the problem and I still cannot solve the remaining two tests for some reason. Below is the code:
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``````#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define pb push_back
#define ALL(v) v.begin(), v.end()
#define RALL(v) v.rbegin(), v.rend()

int main(){
ios::sync_with_stdio(0);
cin.tie(0);

ifstream fin ("photo.in");
ofstream fout ("photo.out");

vector<int> a;
int n, val, x;
fin >> n;

for(int i = 0; i < n-1; i++){
fin >> val;
a.pb(val);
}
vector<int> ans;
for(int i = 1; i < a[0]; i++){
x = i;
for(int j = 0; j < (n-1); j++){
if((a[j] - x)  == x)break;
if((a[j] - x) > n)break;
ans.pb(x);
x = a[j] - x;
}
if(ans.size() == (n-1)){
ans.pb(x);
break;
}else{
ans.clear();
}
}
if(ans.size() == 0){
fout << 0 << '\n';
return 0;
}
for(int i = 0; i < n; i++){
if(i == n-1){
fout << ans[i];
break;
}
fout << ans[i] << " ";
}
fout << '\n';
return 0;
}
``````

Are you remembering to check if your ans vector is forming a permutation? I think there are cases where your vector would form an array of size n with elements from 1 to n but there could be duplicates? You should add in something to make sure that all the values from 1 to n appear exactly once.

1 Like

Thanks! I will implement that to the code and check if the ans vector is a permutation

It’s all good thanks! I just solved it