最短路-Bellman-Ford算法

洛谷:p3371

#include <iostream>
#include <vector>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
#include <algorithm>
#include <numeric>
#include <chrono>
#include <ctime>
#include <cmath>
#include <cctype>
#include <string>
#include <cstdio>
#include <iomanip>


#include <thread>
#include <mutex>
#include <condition_variable>
#include <functional>
#include <iterator>
using namespace std;

const int MAXN = 1e5 + 7;
const int MAXM = 5e5 + 7;
const int INF = 0x7fffffff;

struct Point
{
	int to, next, w;
	Point() :to(0), next(0), w(0) {}
}points[MAXM];

int  heads[MAXN] = { 0 }, visit[MAXN] = { 0 }, d[MAXN] = { 0 }, p[MAXN] = { 0 }, cnt[MAXN] = {0},n, m, s, nCount = 0;

void AddEdge(int from ,int to, int w) {
	points[++nCount].to = to;
	points[nCount].w = w;
	points[nCount].next = heads[from];
	heads[from] = nCount;
}

bool BellmanFord(int s) {
	queue<int> q;
	for (int i = 1; i <= n; ++i) d[i] = INF;

	d[s] = 0;
	visit[s] = true;

	q.push(s);
	while (!q.empty()) {
		int u = q.front(); q.pop();
		visit[u] = false;

		for (int i = heads[u]; i; i = points[i].next) {
			int v = points[i].to;
			int w = points[i].w;
			if (d[u] < INF && d[v] > d[u] + w) {
				d[v] = d[u] + w;
				p[v] = u;
				if (!visit[v]) {
					q.push(v);
					visit[v] = true;
					if (++cnt[v] > n) return false;
				}
			}
		}
	}
	return true;
}
int main()
{
	cin >> n >> m >> s;
	int from ,to ,w;
	for (int i = 0; i < m; i++) {
		cin >> from >> to >> w;
		AddEdge(from, to, w);
	}

	BellmanFord(s);

	for (int i = 1; i <= n; ++i)
		cout << d[i] << " ";

	return 0;
}