P2947 [USACO09MAR] Look Up S

https://www.luogu.com.cn/record/166555989

Luogu/P2947/P2947.cpp

@@ -0,0 +1,37 @@
+#include <iostream>
+#include <stack>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e5 + 5;
+
+int n, h[N], ans[N];
+std::stack<int> st;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> h[i];
+    }
+
+    for (int i = n; i; i--) {
+        // pop all elements that are smaller than h[i]
+        while (!st.empty() && h[i] >= h[st.top()]) st.pop();
+        // if the stack is not empty, the nearest element that is larger than h[i] is st.top()
+        if (!st.empty()) ans[i] = st.top();
+        // push h[i] into the stack
+        st.push(i);
+    }
+
+    for (int i = 1; i <= n; i++) {
+        cout << ans[i] << endl;
+    }
+
+    return 0;
+}