C - Directional Increase

https://codeforces.com/contest/1694/submission/160915609

Codeforces/1694/C/C.cpp

@@ -0,0 +1,35 @@
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+
+    cin >> t;
+
+    while (t--) {
+        bool flag = false, ans = true;
+        int n;
+        long long sum = 0;
+
+        cin >> n;
+
+        for (int i = 1, x; i <= n; i++) {
+            cin >> x;
+
+            if ((sum += x) < 0) ans = false;
+
+            if (sum == 0) flag = true;
+            else if (flag) ans = false;
+        }
+
+        cout << (ans && !sum ? "Yes" : "No") << endl;
+    }
+
+    return 0;
+}