Submission

Score: 100

User: tl.cpp

Problemset: ปริมาตรน้ำท่วม

Language: cpp

Time: 0.002 second

Submitted On: 2025-10-15 11:32:48

#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;
    vector<int> h(n);
    for (int i = 0; i < n; i++) cin >> h[i];

    vector<int> l(n), r(n);
    l[0] = h[0];
    for (int i = 1; i < n; i++) {
        l[i] = max(l[i - 1], h[i]);
    }

    r[n - 1] = h[n - 1];
    for (int i = n - 2; i >= 0; i--) {
        r[i] = max(r[i + 1], h[i]);
    }
    
    long long water = 0;
    for (int i = 0; i < n; i++) {
        int lv= min(l[i], r[i]);
        if (lv > h[i]) water += lv - h[i];
    }
    cout << water;
}