OJ-Problems-Source/HDOJ/4126_autoAC.cpp

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#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<vector>
using namespace std;
const int maxn = 3003;
const int maxm = maxn * maxn;
const int inf = 1000000000;
int n, m;
__int64 mst;
int map[maxn][maxn];
int dp[maxn][maxn];
int dis[maxn], pre[maxn];
bool vis[maxn];
vector<int> edge[maxn];
int minz(int a, int b)
{
return a < b ? a : b;
}
void init()
{
int i, j;
for(i = 0; i < n; i++)
{
for(j = 0; j < n; j++)
map[i][j] = dp[i][j] = inf;
edge[i].clear();
vis[i] = 0;
pre[i] = -1;
dis[i] = inf;
}
}
void input()
{
int x, y, z;
while(m--)
{
scanf("%d%d%d", &x, &y, &z);
map[x][y] = map[y][x] = z;
}
}
void prim()
{
int i, j, k;
for(i = 1; i < n; i++)
{
dis[i] = map[0][i];
pre[i] = 0;
}
dis[0] = inf;
vis[0] = 1;
pre[0] = -1;
mst = 0;
for(i = 0; i < n-1; i++)
{
k = 0;
for(j = 1; j < n; j++)
if(!vis[j] && dis[k] > dis[j])
k = j;
vis[k] = 1;
mst += dis[k];
if(pre[k] != -1)
edge[k].push_back(pre[k]),
edge[pre[k]].push_back(k);
for(j = 1; j < n; j++)
if(!vis[j] && dis[j] > map[k][j] )
dis[j] = map[k][j], pre[j] = k;
}
}
int dfs(int pos, int u, int fa)
{
int i, ans = inf;
for(i = 0; i < edge[u].size(); i++)
{
int v = edge[u][i];
if(v == fa) continue;
int tmp = dfs(pos, v, u);
ans = minz(ans, tmp);
dp[u][v] = dp[v][u] = minz(dp[u][v], tmp);
}
if(pos != fa)
ans = minz(ans, map[pos][u]);
return ans;
}
void solve()
{
int i;
for(i = 0; i < n; i++)
dfs(i, i, -1);
}
void query()
{
int x, y, z;
double sum = 0;
scanf("%d", &m);
for(int ii = 1; ii <= m; ii++)
{
scanf("%d%d%d", &x, &y, &z);
if(pre[x] != y && pre[y] != x)
sum += mst * 1.0;
else
sum += mst * 1.0 - map[x][y] + minz(dp[x][y], z);
}
printf("%.4f\n", sum/m);
}
int main()
{
while( ~scanf("%d%d", &n, &m) && n + m)
{
init();
input();
prim();
solve();
query();
}
return 0;
}