kruskal_并查集_代码模板_hdu1232

kruskal代码模板

input

a b
v1 v2 w1
v2 v3 w2
...

a_the number of verteices

b_the number of edges

v1_verteices

wi_the weight of each edge

#include<iostream>
#include<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<ctype.h>
#include<algorithm>
#include<map>
#include<vector>
#include<set>

#define MAX 100005
#define MOD 1000003
#define inf 100000000
#define eps 1e-9
#define pi acos(-1.0)
#define LL long long
#define I64 __int64
#define max(a, b) ((a) > (b) ? (a) : (b))
#define min(a, b) ((a) < (b) ? (a) : (b))

using namespace std;

struct edge {
int v1, v2, w;
};

int edge_num, vertex_num;
edge volume_e[30];
int father[30];

int cmp(edge a, edge b) {
return a.w < b.w;
}

int find(int x) {
int root = x;
if(father[root] != root)
root = father[root];
return root;
}

int judge(edge e) {
if(find(e.v1) != find(e.v2))
return 1;
return 0;

}
int main()
{
freopen("in.txt", "r", stdin);
cin >> edge_num >> vertex_num;// the number of edge and vertex
// v1, v2, weight
for(int i = 0; i < edge_num; i++)
scanf("%d %d %d", &volume_e[i].v1, &volume_e[i].v2, &volume_e[i].w);

// initial
for(int i = 1; i <= vertex_num; i++) father[i] = i;

sort(volume_e, volume_e+edge_num, cmp);

int sum = 0;
for (int i = 0;i < edge_num;i ++)
{
int x = find (volume_e[i].v1);
int y = find (volume_e[i].v2);
if (x != y)
{
sum += volume_e[i].w;
father[x] = y;
}
}
printf ("%d\n", sum);
}

/*
5 5
1 2 2
2 3 3
1 4 1
3 4 2
4 5 4

*/

hdu1232

using namespace std;

int add;
int f[100010];
int n, m;

int findset(int x)
{
int set = x;
while(f[set] != set)
{
set = f[set];
}
return set;
}

void merge(int a, int b)
{
int x = findset(a);
int y = findset(b);
if(x != y)
f[x] = y;
}

int main()
{
freopen("in.txt", "r", stdin);
while(scanf("%d %d", &n, &m) == 2)
{
add = 0;
if(n == 0)
break;
else if(m == 0)
{
add = n - 1;
printf("%d\n", add);
}
else
{
for(int i = 1; i <= n; i++) f[i] = i;

for(int i = 0; i < m; i++)
{
int a, b;
scanf("%d %d", &a, &b);
merge(a, b);
}

for(int i = 1; i <= n; i++)
if(f[i] == i)
add++;
add--;
printf("%d\n", add);
}
//
memset(f, 0, sizeof(f));
}
}

/*
4 2
1 3
4 3
3 3
1 2
1 3
2 3
5 2
1 2
3 5
999 0
0

*/