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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. #define MOD 1000000007
  6. double pi = acos(-1);
  7. void fast() {ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);}
  8.  
  9. unsigned long long modex(unsigned long long a, unsigned long long b, unsigned long long m) {
  10.     if(b == 0) return 1;
  11.     unsigned long long x = modex(a, b/2, m)%m;
  12.     x = (x*x)%m;
  13.     if(b % 2) x *= a;
  14.     return x%m;
  15. }
  16. unsigned long long modinv(unsigned long long b) { return modex(b, MOD - 2, MOD); }
  17.  
  18. int main() {
  19.     fast();
  20.     //freopen("func.in", "r", stdin);
  21.     // freopen("output.out", "w", stdout);
  22.     int t;
  23.     t = 1;
  24.     cin >> t;
  25.  
  26.  
  27.     while(t --) {
  28.         int n;
  29.         cin >> n;
  30.  
  31.         vector <long long> v(n);
  32.  
  33.         for(int i = 0; i < n; i ++) {
  34.             cin >> v[i];
  35.         }
  36.  
  37.         long long lastMax = -1e10;
  38.         long long lastSum = 0;
  39.         string sol = "YES";
  40.         for(int i = 0; i < n; i ++) {
  41.             if(lastSum <= 0) {
  42.                 lastSum = v[i];
  43.                 lastMax = v[i];
  44.             } else {
  45.                 lastSum += v[i];
  46.                 lastMax = max(v[i], lastMax);
  47.             }
  48.  
  49.             if(lastSum > lastMax) {
  50.                 sol = "NO";
  51.                 break;
  52.             }
  53.         }
  54.  
  55.         lastMax = -1e10;
  56.         lastSum = 0;
  57.         for(int i = n-1; i >= 0; i --) {
  58.             if(lastSum <= 0) {
  59.                 lastSum = v[i];
  60.                 lastMax = v[i];
  61.             } else {
  62.                 lastSum += v[i];
  63.                 lastMax = max(v[i], lastMax);
  64.             }
  65.  
  66.             if(lastSum > lastMax) {
  67.                 sol = "NO";
  68.                 break;
  69.             }
  70.         }
  71.  
  72.         cout << sol << "\n";
  73.     }
  74. }
Success #stdin #stdout 0.01s 5316KB
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YES
https://ideone.com/mnFtIx
language:
C++ (gcc 8.3)
created:
2 years ago
visibility:
secret

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