Dijkstra 算法

洛谷 P4779 【模板】单源最短路径（标准版）

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using p = pair<int, int>;
const double pi(acos(-1));
const int inf(0x3f3f3f3f);
const ll _inf(0x3f3f3f3f3f3f3f3f);
const int mod(1e9 + 7);
const int maxn(1e5 + 10);
const int maxm(2e5 + 10);
int ecnt, head[maxn];
ll dis[maxn];
bool vis[maxn];

struct edge {
    int to, wt, nxt;
} edges[maxm];

template<typename T = int>
inline const T read()
{
    T x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        x = (x << 3) + (x << 1) + ch - '0';
        ch = getchar();
    }
    return x * f;
}

template<typename T>
inline void write(T x, char c)
{
    if (x < 0) {
        putchar('-');
        x = -x;
    }
    if (x > 9) write(x / 10, false);
    putchar(x % 10 + '0');
    if (c) putchar(c);
}

void addEdge(int u, int v, int w)
{
    edges[ecnt].to = v;
    edges[ecnt].wt = w;
    edges[ecnt].nxt = head[u];
    head[u] = ecnt++;
}

void dijkstra(int src)
{
    priority_queue<p, vector<p>, greater<p>> q;
    q.push(p(0, src));
    dis[src] = 0;
    while (not q.empty()) {
        int u = q.top().second;
        q.pop();
        if (vis[u]) continue;
        vis[u] = true;
        for (int i = head[u]; ~i; i = edges[i].nxt) {
            int v = edges[i].to, w = edges[i].wt;
            if (dis[v] > dis[u] + w) {
                dis[v] = dis[u] + w;
                q.push(p(dis[v], v));
            }
        }
    }
}

int main()
{
#ifdef ONLINE_JUDGE
#else
    freopen("input.txt", "r", stdin);
#endif
    memset(head, -1, sizeof head);
    memset(dis, 0x3f, sizeof dis);
    int n = read(), m = read(), s = read();
    while (m--) {
        int u = read(), v = read(), w = read();
        addEdge(u, v, w);
    }
    dijkstra(s);
    for (int i = 1; i <= n; ++i) {
        write(dis[i] == _inf ? INT_MAX : dis[i], i == n ? '\n' : ' ');
    }
    return 0;
}