并查集

来源：互联网发布：网络管理师考试编辑：程序博客网时间：2024/05/17 01:43

题目链接：点击打开链接

#include<cstdio>#define MAXN 1000 + 10int fa[MAXN];int find_set(int i){    if(fa[i] == i) return i;    else return (find_set(fa[i]));}void union_set(int x,int y){    int root_x = find_set(x);    int root_y = find_set(y);    if(root_x != root_y) fa[root_x] = root_y;}int main(){    int n,m;    int x,y;    while(scanf("%d",&n) > 0)    {        if(!n) break;        scanf("%d",&m);        for(int i = 1; i <= n; i++) fa[i] = i;        for(int i = 1; i <= m; i++)        {        scanf("%d%d",&x,&y);        union_set(x,y);        }        int result = 0;        for(int i = 1; i <= n; i++) if(fa[i] == i) result ++;        printf("%d\n",result - 1);    }    return 0;}

使用rank和路径压缩优化后的代码如下：

#include<cstdio>#define MAXN 1000 + 10int fa[MAXN];struct Node {int father;int rank;}node[MAXN];int find_set(int i){if(node[i].father == i) return i;else{ node[i].father = find_set(node[i].father);return node[i].father;}}void union_set(int x,int y){int root_x = find_set(x);int root_y = find_set(y);if(root_x != root_y){if (node[root_x].rank > node[root_y].rank){node[root_y].father = root_x;node[root_x].rank ++;} else{node[root_x].father = root_y;node[root_y].rank++;}}}int main(){int n,m;int x,y;while(scanf("%d",&n) > 0){if(!n) break;scanf("%d",&m);for(int i = 1; i <= n; i++){node[i].father = i;node[i].rank = 0;}for(int i = 1; i <= m; i++){scanf("%d%d",&x,&y);union_set(x,y);}int result = 0;for(int i = 1; i <= n; i++) if(node[i].father == i) result ++;printf("%d\n",result - 1);}return 0;}

但是效果不是很好。。。。下图中109ms为优化后的运行时间。呵呵。。

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