洛谷 P1194 买礼物

题目传送门

2019.8.7,Mr^Simon蒟蒻水题T1

解题思路:

最小生成树的裸题.

AC代码:

#include<cstdio>
#include<iostream>
#include<algorithm> 

using namespace std;

int a,b,v,tot,fa[501],cnt,ans;
struct kkk {
    int from,to,v;
}e[250001]; 

bool cmp(kkk a,kkk b) {
    return a.v < b.v;
}

int find_father(int x) {
    if(fa[x] == x) return x;
    return fa[x] = find_father(fa[x]);
}

int main()
{
    scanf("%d%d",&a,&b);
    for(int i = 0;i <= b; i++) fa[i] = i;
    for(int i = 1;i <= b; i++) {
        e[++tot].from = 0;
        e[tot].to = i;
        e[tot].v = a;    
        for(int j = 1;j <= b; j++) {
            scanf("%d",&v);
            if(v != 0) {
                e[++tot].from = i;
                e[tot].to = j;
                e[tot].v = v;
            }
        }
    }
    if(b == 1) {
        printf("%d",a);
        return 0;
    }
    sort(e+1,e+1+tot,cmp);
    for(int i = 1;i <= tot; i++) {
        int x1 = find_father(e[i].from);
        int y1 = find_father(e[i].to);
        if(x1 != y1) {
            ans += e[i].v;
            fa[x1] = y1;
            cnt++;
        }
        if(cnt == b - 1) {
            printf("%d",ans + a);
            return 0;
        }
    }
    return 0;
}