UVA 10985 Rings'n'Ropes

最短路 参考了Staingger的博客

感觉DP的状态记录还是有毛病。可以DFS寻找结果也。

#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <stack>
#include <queue>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define PI 3.1415926535897932626
using namespace std;
int gcd(int a, int b) {return a % b == 0 ? b : gcd(b, a % b);}
#define MAXN 150
const int INF = 0x3f3f3f3f ;
int dp[MAXN][MAXN];
bool vis[MAXN][MAXN];
int N,M,ans;
void init()
{
    scanf("%d%d",&N,&M);
    memset(dp,0x3f,sizeof(dp));
    while (M--)
    {
        int u,v;
        scanf("%d%d",&u,&v);
        dp[u][v] = dp[v][u] = 1;
    }
    for (int k = 0; k < N; k++)
        for (int i = 0; i < N; i++)
          for (int j = 0; j < N; j++)
           dp[i][j] = min(dp[i][j],dp[i][k] + dp[k][j]);
    for (int i = 0; i < N; i++) dp[i][i] = 0;
}
int calcu(int s, int t)
{
    int res[MAXN],cas = 0,cnt = 0;
    for (int k = 0; k < N; k++)
        if (dp[s][k] + dp[k][t] == dp[s][t]) res[cas++] = k;
    for (int i = 0; i < cas; i++)
        for (int j = i + 1; j < cas; j++)
    {
        int a = res[i] , b = res[j];
        if(dp[a][b] == 1 && dp[s][a] != dp[s][b])
            cnt++;
    }
    return cnt;
}
void slove()
{
    for (int i = 0; i < N; i++)
        for (int j = i + 1; j < N; j++)
    {
        if (dp[i][j] != INF)
            ans = max(ans,calcu(i,j));
    }
}
int main()
{
    //freopen("sample.txt","r",stdin);
    int T,kase = 1;
    scanf("%d",&T);
    while (T--)
    {
        init();
        ans = 0;
        slove();
        printf("Case #%d: %d\n",kase++,ans);
    }
    return 0;
}