洛谷 1144 最短路计数 bfs

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 
 5 const int maxn = 100000 + 500;
 6 const int mod = 100003;
 7 int que[maxn];
 8 bool vis[maxn];
 9 int last[maxn], pre[5 * maxn], other[5 * maxn];
10 int dis[maxn], cnt[maxn];
11 int n, m;
12 int x, y;
13 int tot = 0;
14 void bfs(int s) {
15     memset(dis, 127, sizeof(dis));
16     dis[s] = 1;
17     cnt[s] = 1;
18     int h = 0, t = 1;
19     que[1] = s;
20     while (h < t) {
21         h = (h + 1) % maxn;
22         int cur = que[h];
23         for (int p = last[cur]; p; p = pre[p]) {
24             int q = other[p];
25             if (dis[q] == 0) {
26                 dis[q] = dis[cur] + 1;
27                 cnt[q] = cnt[cur];
28                 t = (t + 1) % maxn;
29                 que[t] = q;
30             } else if (dis[q] > dis[cur] + 1) {
31                 dis[q] = dis[cur] + 1;
32                 cnt[q] = cnt[cur];
33                 t = (t + 1) % maxn;
34                 que[t] = q;
35             } else if (dis[q] == dis[cur] + 1) {
36                 cnt[q] = (cnt[q] + cnt[cur]) % mod;
37             }
38         }
39     }
40 }
41 void add(int x, int y) {
42     tot++;
43     pre[tot] = last[x];
44     last[x] = tot;
45     other[tot] = y;
46 }
47 int main () {
48     scanf("%d %d", &n, &m);
49     for (int i = 1; i <= m; i++) {
50         scanf("%d %d", &x, &y);
51         add(x, y);
52         add(y, x);
53     }
54     bfs(1);
55     for (int i = 1; i <= n; i++) {
56         printf("%d\n", cnt[i]);
57     }
58     
59     return 0;
60 }