算法训练营day71

题目：53. 寻宝（第七期模拟笔试） (kamacoder.com)

最小生成树-prim算法

#include<bits/stdc++.h>

using namespace std;

int main(){
    int n, m;
    cin >> n >> m;
    vector<vector<int>> grid(n + 1, vector<int>(n + 1, 10001));
    while(m--) {
        int x, y;
        cin >> x >> y;
        cin >> grid[x][y];
        grid[y][x] = grid[x][y];
    }
    vector<int> minDist(n + 1, 10001);
    vector<bool> isTree(n + 1, false);
    int cur = 1;
    for(int i = 0;i < n;i++) {
        int min = 10001;
        for(int j = 1;j <= n;j++) {
            if(!isTree[j] && minDist[j] < min) {
                min = minDist[j];
                cur = j;
            }
        }
        isTree[cur] = true;
        for(int j = 1;j <= n;j++) {
            if(!isTree[j] && grid[cur][j] < minDist[j]) {
                minDist[j] = grid[cur][j];
            }
        }
    }
    int result = 0;
    for(int i = 2;i <= n;i++) {
        result += minDist[i];
    }
    cout << result << endl;
    return 0;
}

最小生成树-Kruskal 算法

#include<bits/stdc++.h>

using namespace std;

int n = 10001;
vector<int> father(10001, 0);
struct edge{
    int l, r, val;
};

void init() {
    for(int i = 1;i <= n;i++) {
        father[i] = i;
    }
}

int find(int x) {
    return x == father[x] ? x : father[x] = find(father[x]);
}

void join (int u, int v) {
    u = find(u);
    v = find(v);
    if(u == v) return;
    father[v] = u;
}

int main(){
    int m;
    cin >> n >> m;
    vector<edge> edges;
    while(m--) {
        int l, r, val;
        cin >> l >> r >> val;
        edges.push_back({l, r, val});
    }
    
    sort(edges.begin(), edges.end(), [](const edge& a, const edge& b){return a.val < b.val;});
    init();
    int result = 0;
    for(int i = 0;i < edges.size();i++) {
        if(find(edges[i].l) == find(edges[i].r)) continue;
        else {
            result += edges[i].val;
            join(edges[i].l, edges[i].r);
        }
    }
    cout << result << endl;
    
}