kruskal_poj 1251Jungle Roads

poj1251

http://poj.org/problem?id=1251

此題一看就知是最小生成樹，由於數據量很小，輸入的數據形式也沒有那一種比較方便，所以prim和kruskal都可以

下面給出kruskal代碼

 

#include<cstdio>
#include<vector>
#include<cstring>
#include<algorithm>
#include<iostream>

#define MAXEN 200
#define MAXVN 60

using namespace std;

typedef struct{
    int u, v, value;
}Edge;

Edge eg[MAXEN];
int p[MAXVN], rank[MAXVN];
vector<Edge> usedEdge;

void MAKE_SET(int x){
    p[x] = x;
    rank[x] = 0;
}
int FIND_SET(int x){
    if(x != p[x])
        p[x] = FIND_SET(p[x]);
    return p[x];
}
void LINK(int x, int y){
    if(rank[x] > rank[y])  p[y] = x;
    else{
        p[x] = y;
        if(rank[x] == rank[y]) rank[y] += 1;
    }
}

void UNION_SET(int x, int y){
    LINK(FIND_SET(x), FIND_SET(y));
}
int cmp(const void *a, const void *b){
    return (*(Edge *)a).value - (*(Edge *)b).value;
}

bool cp(Edge a,Edge b){
    return a.value < b.value;
}
int kruskal(int en, int vn){
    usedEdge.clear();//printf("sfdds");
    for(int i = 1; i <= vn; i++) MAKE_SET(i);
    qsort(eg,en,sizeof(eg[0]), cmp);
    for(int i = 0; i < en; i++){
        if(FIND_SET(eg[i].u) != FIND_SET(eg[i].v)){
            UNION_SET(eg[i].u,eg[i].v);
            usedEdge.push_back(eg[i]);
        }
    }
    int sum = 0;
    for(int i = 0; i < usedEdge.size(); i++) sum+=usedEdge[i].value;
    return sum;
}

int main(){
    int vn,n, b;
    char a;
    //freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
    while(cin>>vn && vn){
        //getchar();
        int count = 0;
        for(int i = 1; i < vn; i++){
            cin>>a>>n;
            //printf("n: %d\n", n);
            //getchar();
            for(int j = 0; j < n ; j++){
                cin>>a>>b;
                getchar();
                eg[count].u = i;
                eg[count].v = a - 'A' +1;
                eg[count++].value = b;
            }
        }
        int sum = kruskal(count, vn);
        cout<<sum<<endl;
    }
}