算法模板之Dijikstra（HDU 1874 畅通工程续）

//dijikstra
//O(n^2)

/*const int MaxN =  1000;
int dis[MaxN], g[MaxN][MaxN], N; // N 图中的点数， g边之间的距离， dis节点间最短距离
bool v[MaxN];

void dj()
{
for(int i = 0; i <= N; i++)
dis[i] = INF;
dis[1] = 0;
memset(v, 0, sizeof(v));
for(int i = 0; i <= N; i++)
{
int mark = -1, mindis = INF;
for(int j = 1; j <= N; j++)
{
if(!v[j] && dis[j] < mindis)
{
mindis = dis[j];
mark = j;
}
}
if(mark == -1) break;
v[mark] = 1;
for(int j = 1; j <= N; j++)
if(!v[j])
dis[j] = min(dis[j], dis[mark] + g[mark][j]);
}
}*/

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>

using namespace std;

const int MaxN = 10005;
const int INF = 10000005;
int dis[MaxN], g[MaxN][MaxN], N, M;
bool v[MaxN];

void dj(int x)
{
for(int i = 1; i <= N; i++)
dis[i] = INF;
dis[x] = 0;
memset(v, 0, sizeof(v));
for(int i = 1; i <= N; i++)
{
int mark = -1, mindis = INF;
for(int j = 1; j <= N; j++)
{
if(!v[j] && dis[j] < mindis)
{
mindis = dis[j];
mark = j;
}
}
if(mark == -1) break;
v[mark] = 1;
for(int j = 1; j <= N; j++)
if(!v[j])
dis[j] = min(dis[j], dis[mark] + g[mark][j]);
}
}

int main()
{
while(cin >> N >> M)
{
int a, b, x;
for(int i = 1; i <= N; i++)
for(int j = 1; j <= N; j++)
{
if(i == j)	g[i][j] = 0;
else g[i][j] = INF;
}
for(int i = 1; i <= M; i++)
{
cin >> a >> b >> x;
if(g[a + 1][b + 1] > x)
{
g[a + 1][b + 1] = x;
g[b + 1][a + 1] = x;
}
}
cin >> a >> b;

dj(a + 1);
if(dis[b + 1] == INF)
cout << "-1" << endl;
else
cout << dis[b + 1] << endl;
}
return 0;
}