Submission

Score: 100

User: sleepntsheep

Problemset: ปริมาตรน้ำท่วม

Language: cpp

Time: 0.002 second

Submitted On: 2026-07-12 19:28:36

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

long long ans;
int n, a[200001], lft[200001], rght[200001];

int main()
{
    cin >> n;
    for (int i = 1; i <= n; ++i)
    {
        cin >> a[i];
    }

    int mx = 0;
    for (int i = 1; i <= n; ++i)
    {
        mx = max(mx, a[i]);
        lft[i] = mx;
    }
    mx = 0;
    for (int i = n; i >= 1; --i)
    {
        mx = max(mx, a[i]);
        rght[i] = mx;
    }


    for (int i = 1; i <= n; ++i)
    {
        ans += min(lft[i], rght[i]) - a[i];
    }

    cout << ans;

    return 0;
}