题解 | 相邻的糖果

#include <iostream>
#include <vector>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n, m;
    long long x;
    if (!(cin >> n >> m >> x)) return 0;

    vector<long long> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }

    long long sum = 0, count = 0;
    
    // 1. 处理第一个区间
    for (int i = 0; i < m; i++) {
        sum += a[i];
    }

    if (sum > x) {
        long long diff = sum - x;
        count += diff; // 累加总操作数
        
        for (int i = m - 1; i >= 0 && sum > x; i--) {
            if (a[i] > sum - x) {
                a[i] -= (sum - x);
                sum = x; 
            } else {
                sum -= a[i];
                a[i] = 0;
            }
        }
    }

    // 2. 滑动窗口处理后续区间 
    for (int i = m; i < n; i++) {
        sum = sum - a[i - m] + a[i];
        if (sum > x) {
            long long excess = sum - x;
            a[i] -= excess; 
            count += excess;
            sum = x;
        }
    }

    cout << count << endl;
    return 0;
}