最短路径之SPFA

#include <iostream>
#include <cstring>
#include <queue>
#include <algorithm>
#include <cstdio>
using namespace std;

const int maxn = 1e6 + 10;
const int inf = 1e9 + 7;
const int mod = 1e5 + 3;
int head[maxn], d[maxn];
bool inq[maxn];
int inqSum[maxn];
int num[maxn];
int n, m, cnt, s, t;
struct node{
	int v, nex, len;
}edge[maxn * 2];

void addedge(int u, int v, int len)
{
	edge[cnt].v = v;
	edge[cnt].nex = head[u];
	edge[cnt].len = len;
	head[u] = cnt++;
}

void init()
{
	memset(head, -1, sizeof(head));
}

bool spfa()
{
	fill(d, d + maxn, inf);
	d[s] = 0;
	queue<int>que;
	que.push(s);
	num[s] = 1;
	inq[s] = true;
	inqSum[s]++;
	while(!que.empty()) {
		int u = que.front();
		que.pop();
		inq[u] = false;
//		cout << u << " ";
		for(int i = head[u]; i != -1; i = edge[i].nex) {
			int v = edge[i].v;
			if(d[u] + edge[i].len < d[v]) {
				d[v] = d[u] + edge[i].len;
				if(!inq[v])
					que.push(v);
				inq[v] = true;
				inqSum[v]++;
				num[v] = num[u];
				num[v] %= mod;
//				if(inqSum[v] >= n)
//					return false;
			}
			else if(d[u] + edge[i].len == d[v])
				num[v] += num[u], num[v] %= mod;
		}
	}
//	return true;
}

int main()
{
	ios::sync_with_stdio(false);
	init();
	cin >> n >> m;
	s = 1;
	int x, y, z;
	for(int i = 1; i <= m; i++) {
		cin >> x >> y;
		addedge(x, y, 1);
		addedge(y, x, 1);
	}
	spfa();
//	for(int i = 1; i <= n; i++)
//		cout << d[i] << " ";
//	cout << endl;
	for(int i = 1; i <= n; i++)
		cout << num[i] << endl;
	return 0;
}