'commit'

TangDou/LuoGuBook/P2866_3.cpp

@@ -0,0 +1,27 @@
+#include<bits/stdc++.h>
+
+using namespace std;
+typedef long long LL;
+const int N=80010;
+int a[N];
+int res[N];
+stack<int> stk;
+int n;
+LL ans;
+int main() {
+    cin >> n;
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+        while (!stk.empty() && a[stk.top()] <= a[i]) {
+            res[stk.top()] = i;
+            stk.pop();
+        }
+        stk.push(i);
+    }
+
+    for (int i = 1; i <= n; i++) {
+        if (res[i] == 0) ans += n - i;
+        else ans += res[i] - i - 1;
+    }
+    cout << ans;
+}