T263082 区间(range)

https://www.luogu.com.cn/record/85504975

Luogu/T263082/T263082.cpp

@@ -0,0 +1,42 @@
+#include <iostream>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e5 + 5;
+
+int n, a[N], b[N];
+std::vector<std::pair<int, int>> ans;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+
+        b[i] = a[i] - a[i - 1];
+    }
+
+    b[n + 1] = -a[n];
+
+    for (int i = 1, j = 1; i <= n + 1; i++) {
+        while (b[i] < 0) {
+            while (j < i && b[j] <= 0) j++;
+            b[j]--, b[i]++;
+            ans.emplace_back(j, i - 1);
+        }
+    }
+
+    cout << ans.size() << endl;
+
+    for (const auto &e : ans) {
+        cout << e.first << ' ' << e.second << endl;
+    }
+
+    return 0;
+}