今日语录:成功不是终点,失败不是致命,勇气才是取胜的关键。文章来源:https://www.toymoban.com/news/detail-820518.html
prim算法
#include <cstring>
#include <algorithm>
#include <iostream>
#define _CRT_SECURE_NO_WARNINGS
using namespace std;
const int N = 510,INF = 0x3f3f3f3f;
int n, m;
int g[N][N];
int dist[N];
bool st[N];
int prim()
{
memset(dist, 0x3f, sizeof dist);
int res = 0;
for (int i = 0; i < n; i++)
{
int t = -1;
for (int j = 1; j <= n; j++)
if (!st[j] && (t == -1 || dist[t] > dist[j]))
t = j;
if (i && dist[t] == INF)return INF;
if (i)res += dist[t];
for (int j = 1; j <= n; j++)dist[j] = min(dist[j], g[t][j]);
st[t] = true;
}
return res;
}
int main()
{
scanf("%d%d", &n, &m);
memset(g, 0x3f, sizeof g);
while (m--)
{
int a, b,c;
scanf("%d%d%d", &a, &b, &c);
g[a][b] = g[b][a] = min(g[a][b], c);
}
int t = prim();
if (t == INF)puts("impossible");
else printf("%d\n", t);
return 0;
}
kruskal算法(稀疏图)
#include <algorithm>
#include <iostream>
#define _CRT_SECURE_NO_WARNINGS
using namespace std;
const int N = 10010;
int n, m;
int p[N];
struct Edge
{
int a, b, w;
bool operator< (const Edge& W)const
{
return w < W.w;
}
}edges[N];
int find(int x)
{
if (p[x] != x)p[x] = find(p[x]);
return p[x];
}
int main()
{
scanf("%d%d", &n, &m);
for (int i = 0; i < m; i++)
{
int a, b, w;
scanf("%d%d%d", &a, &b, &w);
edges[i] = { a,b,w };
}
sort(edges, edges + m);
for (int i = 1; i <= n; i++)p[i] = i;
int res = 0, cnt = 0;
//res存储最小生成树中的权重之和
//cnt存储的是当前存储了多少条边
for (int i = 0; i < m; i++)
{
int a = edges[i].a, b = edges[i].b, w = edges[i].w;
a = find(a), b = find(b);
if (a != b)
{
p[a] = b;
res += w;
cnt++;
}
}
if (cnt < n - 1)puts("impossible");
else printf("%d\n", res);
return 0;
}
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