AcWing903 昂贵的聘礼（最短路）

Posted 2021-02-20 ctyakwf

本题我们可以把物品当作一个点，并且设立一个虚拟原点，然后加上一个限制是不能超过m个等级

因此枚举每个范围求一遍最短路就行，因为我们发现等级差距并不是很大，注意，酋长不一定是最大等级

#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

const int N = 110, INF = 0x3f3f3f3f;

int n, m;
int w[N][N], level[N];
int dist[N];
bool st[N];

int dijkstra(int down, int up)
{
    memset(dist, 0x3f, sizeof dist);
    memset(st, 0, sizeof st);

    dist[0] = 0;
    for (int i = 1; i <= n + 1; i ++ )
    {
        int t = -1;
        for (int j = 0; j <= n; j ++ )
            if (!st[j] && (t == -1 || dist[t] > dist[j]))
                 t = j;

        st[t] = true;
        for (int j = 1; j <= n; j ++ )
            if (level[j] >= down && level[j] <= up)
                dist[j] = min(dist[j], dist[t] + w[t][j]);
    }

    return dist[1];
}

int main()
{
    cin >> m >> n;

    memset(w, 0x3f, sizeof w);
    for (int i = 1; i <= n; i ++ ) w[i][i] = 0;

    for (int i = 1; i <= n; i ++ )
    {
        int price, cnt;
        cin >> price >> level[i] >> cnt;
        w[0][i] = min(price, w[0][i]);
        while (cnt -- )
        {
            int id, cost;
            cin >> id >> cost;
            w[id][i] = min(w[id][i], cost);
        }
    }

    int res = INF;
    for (int i = level[1] - m; i <= level[1]; i ++ ) res = min(res, dijkstra(i, i + m));

    cout << res << endl;

    return 0;
}

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