HDU1213 How Many Tables(并查集)
题意:
请客吃饭,认识的才能坐一桌,每次给两个认识的人,求需要多少桌
要点:
并查集裸题,就是多了一个求最后集合个数的步骤,要求最后集合个数,只要每次合并的时候当前集合数-1即可
16672187 | 2016-03-25 21:55:04 | Accepted | 1213 | 0MS | 1728K | 738 B | C++ | seasonal |
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define maxn 1050
int m,n,num;
int p[maxn],rank[maxn];
void init()
{
for (int i = 1; i <= m; i++)
{
p[i] = i;
rank[i] = 0;
}
}
int find(int x)
{
if (p[x] == x) return x;
else p[x] = find(p[x]);
}
void merge(int x, int y)
{
x = find(x);
y = find(y);
if (x == y) return;
if (rank[x] > rank[y])
{
p[y] = x;
num--;
}
else
{
p[x] = y;
if (rank[x] == rank[y]) rank[y]++;
num--;//当前集合数-1,最后求出剩余集合数
}
}
int main()
{
int t,i,x,y;
scanf("%d", &t);
while (t--)
{
scanf("%d%d", &m, &n);
init();
num = m;
for (i = 0; i < n; i++)
{
scanf("%d%d", &x, &y);
merge(x, y);
}
printf("%d\n", num);
}
return 0;
}