break point 在 边数很少，o(n*m)暴力出奇迹~~~
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#include<iostream>#include<map>#include<string>#include<cstdio>#include<cstring>#include<algorithm>#include<queue>using
namespace std;const
int maxn = 1005, maxm = 22222, inf=2000;int
n, m, cnt;int
h[maxn], d[maxn][maxn];map<string, int> mp;struct
edge{ int
v, nxt;}e[maxm];void
add(int
u, int
v){ e[cnt] = (edge){v, h[u]}; h[u]=cnt++; e[cnt]=(edge){u, h[v]}; h[v]=cnt++; d[u][v]=d[v][u]=1;}int
vis[maxn];void
dijkstra(const
int s){ queue<int> q; memset(vis, 0, sizeof(vis)); q.push(s); vis[s]=1; while(!q.empty()){ int
u = q.front(); q.pop(); for(int
i=h[u]; i!=-1; i=e[i].nxt){ int
v = e[i].v; if(vis[v]) continue; d[v][s]=d[s][v]=min(d[s][v], d[s][u]+1); q.push(v), vis[v]=1; } }}int
main(){ while(scanf(" %d", &n)==1 && n){ int
i, j; string s1, s2; char
n1[12], n2[12]; mp.clear(); for(i=0; i<n; i++){ scanf(" %s", n1); mp[s1=n1]=i; } cnt=0; memset(h, -1, sizeof(h)); for(i=0; i<n; i++) for(j=0; j<n; j++) d[i][j]=i==j?0:inf; scanf(" %d", &m); while(m--){ scanf(" %s %s", n1, n2); add(mp[s1=n1], mp[s2=n2]); } for(i=0; i<n; i++) dijkstra(i); int
ans = 0; for(i=0; i<n; i++) for(j=i+1; j<n; j++){ ans=max(ans, d[i][j]); } printf("%d\n", ans==inf?-1:ans); } return
0;} |
原文：http://www.cnblogs.com/ramanujan/p/3775029.html