poj 1251; zoj 1406 Jungle Roads[ MST ]

题目连接 http://poj.org/problem?id=1251

代码

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

int parent[257];
int n, m;
struct node {
	char u, v;
	int w;
};
struct node a[101];

int cmp(const void *a, const void *b)
{
	struct node c = *(struct node *)a;
	struct node d = *(struct node *)b;
	return c.w - d.w;
}

int Find(int x)
{
	int s = x;
	while( parent[s] >= 0 ) {
		s = parent[s];
	}
	while(s != x) {
		int tmp = parent[x];
		parent[x] = s;
		x = tmp;
	}
	return s;
}

int Union(int R1, int R2) 
{
	int r1 = Find(R1);
	int r2 = Find(R2);
	if(r1 == r2) return 0;
	int tmp = parent[r1] + parent[r2];
	if(parent[r1] > parent[r2]) {
		parent[r1] = r2;
		parent[r2] = tmp;
	} else {
		parent[r2] = r1;
		parent[r1] = tmp;
	}
	return 1;
}

int Kruskal()
{
	int ans = 0;
	int edge = 0;
	for(int i = 0; i < m; i++) {
		int R1 = a[i].u;
		int R2 = a[i].v;
		if(Union(R1, R2)) {
			ans += a[i].w;
			edge++;
		}
		if(edge >= n-1) break;
	}
	return ans;
}

int main()
{
	while(scanf("%d%*c", &n), n) {
		char c;
		int t;
		m = 0;
		for(int i = 0; i < n-1; i++) {
			scanf("%c %d%*c", &c, &t);
			for(int j = 0; j < t; j++) {
				char cc;
				int w;
				scanf("%c %d%*c", &cc, &w);
				a[m].u = c;
				a[m].v = cc;
				a[m].w =w;
				m++;
			} 
		}
		memset(parent, -1, sizeof(parent));
		qsort(a, m, sizeof(struct node), cmp);
		printf("%d\n", Kruskal());
	}
	return 0;
}

　　上面代码在ｚｏｊ上ＡＣ，但是在ｐｏｊ上会ＲＥ或ＴＬＥ，主要是输入的问题，把输入改成下面的代码就可以了，其实我也不知道为什么这么改。

for(int i = 0; i < n-1; i++) {
			scanf(" %c %d", &c, &t);
			for(int j = 0; j < t; j++) {
				char cc;
				int w;
				scanf(" %c %d", &cc, &w);
				a[m].u = c;
				a[m].v = cc;
				a[m].w =w;
				m++;
			} 
		}