python/TangDou/Topic/PrefixAndSuffix/P3406.cpp

#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
#define int long long
#define endl "\n"
int p[N]; // 要访问的城市顺序
int a[N]; // 买票
int b[N]; // 充值
int c[N]; // 买卡
int q[N]; // 差分数组
int res;

// 数据范围是10^5*10^5,所以注意要开ll
signed main() {
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; i++) cin >> p[i];                      // 记录访问顺序
    for (int i = 1; i <= n - 1; i++) cin >> a[i] >> b[i] >> c[i]; // 输入价格

    for (int i = 1; i < m; i++) { // 起点到终点，差分修改
        int t1 = p[i - 1];
        int t2 = p[i];
        if (t1 > t2)
            q[t2] += 1, q[t1] -= 1;
        else
            q[t1] += 1, q[t2] -= 1;
    }
    for (int i = 1; i <= n; i++) q[i] += q[i - 1]; // 前缀和处理

    // 判断一下 n*a[i]和n*b[i]+c[i]的大小
    for (int i = 1; i < n; i++)
        res += min(q[i] * a[i], q[i] * b[i] + c[i]);

    cout << res << endl;
}