some programs!!!

dsa/ch2_linear_list/P2629_good_news.cpp

@@ -0,0 +1,60 @@
+#include <iostream>
+
+constexpr int MAX_N = 1e6 + 1;
+int n, ans = 0;
+int values[MAX_N], sums[MAX_N], min_sums[2][MAX_N];
+
+void init_sums() {
+    sums[0] = values[0];
+    for (int i = 1; i < n; i++) {
+        sums[i] = sums[i - 1] + values[i];
+    }
+}
+
+void init_min_sums() {
+    min_sums[0][0] = sums[0];
+    for (int i = 1; i < n; i++) {
+        min_sums[0][i] = std::min(min_sums[0][i - 1], sums[i]);
+    }
+    min_sums[1][n - 1] = sums[n - 1];
+    for (int i = n - 2; i >= 0; i--) {
+        min_sums[1][i] = std::min(min_sums[1][i + 1], sums[i]);
+    }
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    std::cin.tie(nullptr);
+
+    std::cin >> n;
+    for (int i = 0; i < n; i++) {
+        std::cin >> values[i];
+    }
+    init_sums();
+    init_min_sums();
+
+    for (int i = 0; i < n - 1; i++) {
+        int delta1 = sums[i];
+        int delta2 = sums[n - 1] - sums[i];
+        if (min_sums[0][i] + delta2 >= 0 && min_sums[1][i + 1] - delta1 >= 0) {
+            std::clog << i << std::endl;
+            ans++;
+        }
+    }
+
+    bool flag = false;
+    for (int i = 0; i < n; i++) {
+        if (sums[i] < 0) {
+            flag = true;
+            break;
+        }
+    }
+    if (!flag) {
+        std::clog << n - 1 << std::endl;
+        ans++;
+    }
+
+    std::cout << ans << std::endl;
+
+    return 0;
+}