[最短路Floyd]，启动！！！

B3647 【模板】Floyd

#include<bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pb push_back
#define PII pair<int,int >
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std;
const int N = 405;
int n,m;
int dis[N][N];
void floyd()
{
	for(int k=1;k<=n;k++)
	{
		for(int i=1;i<=n;i++)
		{
			for(int j=1;j<=n;j++)
			{
				dis[i][j] = min(dis[i][j],dis[i][k]+dis[k][j]);
			}
		}
	}
}
int main()
{
	IOS;
	cin>>n>>m;
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)
		{
			dis[i][j] = 1e9;
			if(i==j) dis[i][j] = 0;
		}
	}
	while(m--)
	{
		int a,b,w;
		cin>>a>>b>>w;
		dis[a][b] = min(dis[a][b],w);
		dis[b][a] = min(dis[b][a],w);//双向边
	}
	floyd(); 
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)
		{
			cout<<dis[i][j]<<" ";
		}
		cout<<"\n";
	}
}

P1744 采购特价商品

#include<bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pb push_back
#define PII pair<int,int >
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std;
const int N = 300;
int n,m;
double dis[300][300];
struct Node{
	int x;
	int y;
}va[N];
void flyod()
{
	for(int k=1;k<=n;k++)
	{
		for(int i=1;i<=n;i++)
		{
			for(int j=1;j<=n;j++)
			{
				dis[i][j] = min(dis[i][j],dis[i][k]+dis[k][j]);
			}
		}
	}
}
int main()
{
//	IOS;
	cin>>n;
	for(int i=1;i<=n;i++) cin>>va[i].x>>va[i].y;
	cin>>m;
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)
		{
			dis[i][j] = 1e9;
			if(i==j) dis[i][j] = 0;
		}
	}
	for(int i=1;i<=m;i++)
	{
		int a,b;
		cin>>a>>b;
		double w = sqrt( (va[a].x-va[b].x)*(va[a].x-va[b].x)+(va[a].y-va[b].y)*(va[a].y-va[b].y) );
		dis[a][b] = min(dis[a][b],w);
		dis[b][a] = min(dis[b][a],w);
	}
	flyod();
	int s,t;
	cin>>s>>t;
	printf("%.2lf",dis[s][t]);
}

P2888 [USACO07NOV] Cow Hurdles S

#include<bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pb push_back
#define PII pair<int,int >
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std;
const int N = 400;
int n,m,T;
int dis[N][N];
void floyd()
{
	for(int k=1;k<=n;k++)
	{
		for(int i=1;i<=n;i++)
		{
			for(int j=1;j<=n;j++)
			{
				dis[i][j] = min(dis[i][j],max(dis[i][k],dis[k][j]));
			}
		}
	}
}
int main()
{
	IOS;
	cin>>n>>m>>T;
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)
		{
			dis[i][j] = 1e9;
			if(i==j) dis[i][j] = 0;
		}	
	}
	while(m--)
	{
		int a,b,w;
		cin>>a>>b>>w;
		dis[a][b] = min(dis[a][b],w);
	}
	floyd();
	while(T--)
	{
		int a,b;
		cin>>a>>b;
		if(dis[a][b]==1e9) cout<<-1<<"\n";
		else cout<<dis[a][b]<<"\n";
	}
}

P1364 医院设置

#include<bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pb push_back
#define PII pair<int,int >
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std;
const int N = 200;
int n;
int dis[N][N];
int va[N];
void floyd()
{
	for(int k=1;k<=n;k++)
	{
		for(int i=1;i<=n;i++)
		{
			for(int j=1;j<=n;j++)
			{
				dis[i][j] = min(dis[i][j],dis[i][k]+dis[k][j]);
			}
		}
	}
}
int main()
{
	IOS;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)
		{
			dis[i][j] = 1e9; 
			if(i==j) dis[i][j] =0;
		}
	}
	for(int i=1;i<=n;i++)
	{
		int a,b;
		cin>>va[i]>>a>>b;
		if(b!=0) dis[i][b] = min(dis[i][b],1),dis[b][i] =min(dis[b][i],1);
		if(a!=0) dis[i][a] = min(dis[i][a],1),dis[a][i] = min(dis[a][i],1);
	}
	floyd();
	int minn =1e9;
	for(int i=1;i<=n;i++)
	{
		int sum = 0;
		for(int j=1;j<=n;j++)
		{
			sum += dis[i][j]*va[j];
		}
		minn = min(sum,minn);
	}
	cout<<minn;
}

P1359 租用游艇

#include<bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pb push_back
#define PII pair<int,int >
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std;
const int N = 400;
int n,m;
int dis[N][N];
void floyd()
{
	for(int k=1;k<=n;k++)
	{
		for(int i=1;i<=n;i++)
		{
			for(int j=1;j<=n;j++)
			{
				dis[i][j] = min(dis[i][j],dis[i][k]+dis[k][j]);
			}
		}
	}
}
int main()
{
	IOS;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)
		{
			dis[i][j] = 1e9;
			if(i==j) dis[i][j] = 0;
		}
	}
	for(int i=1;i<=n-1;i++)
	{
		for(int j=i+1;j<=n;j++)
		{
			int w;
			cin>>w;
			dis[i][j] = min(dis[i][j],w);
		}
	}
	floyd();
	cout<<dis[1][n];
}