UVA Page Hopping（Floyd算法）

#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<cctype>
#include<list>
#include<iostream>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<vector>

using namespace std;

#define FOR(i, s, t) for(int i = (s) ; i <= (t) ; ++i)
#define REP(i, n) for(int i = 0 ; i < (n) ; ++i)

int buf[10];
inline long long read()
{
long long x=0,f=1;
char ch=getchar();
while(ch<'0'||ch>'9')
{
if(ch=='-')f=-1;
ch=getchar();
}
while(ch>='0'&&ch<='9')
{
x=x*10+ch-'0';
ch=getchar();
}
return x*f;
}

inline void writenum(int i)
{
int p = 0;
if(i == 0) p++;
else while(i)
{
buf[p++] = i % 10;
i /= 10;
}
for(int j = p - 1 ; j >= 0 ; --j) putchar('0' + buf[j]);
}
/**************************************************************/
#define MAX_N 110
const int INF = 0x3f3f3f3f;
int G[MAX_N][MAX_N];
map<int, int> mp;
int main()
{
int n, m;
int cas = 1;
while(~scanf("%d%d", &n, &m) && (n + m))
{
memset(G, INF, sizeof(G));
for(int i = 0 ; i < MAX_N ; i++)
G[i][i] = 0;
mp.clear();
int t = 0;
if(!mp.count(n))
{
mp
= t++;
}
if(!mp.count(m))
{
mp[m] = t++;
}
int u = mp
;
int v = mp[m];
G[u][v] = 1;

while(scanf("%d%d", &n, &m) && (n + m))
{
if(!mp.count(n))
{
mp
= t++;
}
if(!mp.count(m))
{
mp[m] = t++;
}
int u = mp
;
int v = mp[m];
G[u][v] = 1;
}
int cnt = mp.size();
int sum = 0;
for(int k = 0 ; k < cnt ; k++)
for(int i = 0 ; i < cnt ; i++)
for(int j = 0 ; j < cnt ; j++)
{
G[i][j] = min(G[i][j], G[i][k] + G[k][j]);
}
for(int i = 0 ; i < cnt ; i++)
for(int j = 0 ; j < cnt ; j++)
{
sum += G[i][j];
}
double ans = (sum + 0.0)/ (cnt * (cnt - 1));
printf("Case %d: average length between pages = %.3f clicks\n", cas++, ans);
}

return 0;
}