朴素版本

#include<bits/stdc++.h>
using namespace std;
const int maxn = 10010;
const int inf = 0x3f3f3f3f;
int a[maxn][maxn],dis[maxn],visit[maxn],n,m,s,t;
void init() {for(int i = 1; i <= n; i++)for(int j = 1; j <= n; j++)if(i == j)	a[i][j] = 0;else	a[i][j] = inf;
}
void Dij() {for(int i = 1; i <= n; i++)	dis[i] = a[s][i];dis[s] = 0, visit[s] = 1;int minn,su;for(int j = 1; j < n; j++) {minn = inf, su = -1;for(int i = 1; i <= n; i++)if(!visit[i] && dis[i] < minn) {minn = dis[i];su = i;}visit[su] = 1;for(int i = 1; i <= n; i++)if(!visit[i])dis[i] = min(dis[i],dis[su] + a[su][i]);}cout << dis[t] <<endl;
}
int main() {cin >> n >> m >> s >> t;init();for(int i = 1; i <= m; i++) {int x,y;cin >> x >> y;cin >> a[x][y];}Dij();return 0;
}

堆优化加链式向前星

#include<bits/stdc++.h>
using namespace std;
const int inf = 0x3f3f3f3f;
const int maxn = 1e5 + 10;
struct edge {int to,value,next;
}a[2 * maxn];
struct node {int x,pos;node(int a,int b) : x(a), pos(b) { }bool operator < (const node &t) const {return t.x < x;}
};
int n, m, visit[maxn], dis[maxn], s, head[maxn],cnt = 1;
void add(int x,int y,int z) {a[cnt].to = y;a[cnt].value = z;a[cnt].next = head[x];head[x] = cnt++;
}
void Dij () {for(int i = 1; i <= n; i++)	dis[i] = inf;dis[s] = 0; visit[s] = 1;priority_queue<node>q;q.push(node(0,s));while(!q.empty()) {node temp = q.top();q.pop();int x = temp.x, pos = temp.pos;if(dis[pos] < x) continue;for(int i = head[pos]; i; i = a[i].next) {if(dis[a[i].to] > dis[pos] + a[i].value) {dis[a[i].to] = dis[pos] + a[i].value;q.push(node(dis[a[i].to],a[i].to));}}}for(int i = 1; i <= n; i++)cout << dis[i] << " ";cout <<endl;
}
int main() {int x, y, z;cin >> n >> m >> s;for(int i = 0; i < m; i++) {cin >> x >> y >> z;add(x,y,z);}Dij();return 0;
}