Henan 2014 provincial Race world's gateway topological sorting

10404:e. World of William Time Limit:2 Sec Memory limit:128 MB
Submit:2 solved:1
[Submit] [Status] [Web Board] Description

an empire has a N a new type of weapon known as the "World's Gateway". Now for the sake of the country's economic development, it needs a lot of money, and for this reason, the Imperial President OBM is ready to sell some weapons to other countries.

The president of this Empire OBM know, it N may be restricted to each other. For example, the 3 weapons would defeat the first 1 weapons, and the first 4 weapons would defeat section 3 Kinds of weapons and so on. He hoped that at least one of the weapons sold was in his hands, with the aim that the Empire could restrain the rest of the world, so that it could maintain its hegemonic position on the Earth.

but the President OBM the mind is a bit stupid, he wants to know how many weapons he can sell, would you like to help him?

( You can tell the computer, but don't tell him.) )

Input

First line: K indicates how many sets of test data are available.

Next to each set of test data:

1 Span style= "font-size:14px" > line :        N                  new type

2~n+1 line: A 1   a 2 a n      i a i

1≤k≤10 0≤n≤106 1≤ai≤n

Output

for each set of test data, the output takes one line: The maximum number of weapons that can be sold

Sample Input

172 3 1 3 6 5 4

Sample Output

3

#include <cstdio> #include <iostream> #include <algorithm> #include <queue> #include <stack > #include <climits> #include <cstring> #include <cmath> #include <map> #include <set># Define INF 100000000using namespace Std;int a[100005],d[100005],vis[100005];int main () {int t;cin >> t;while (T--) { int n;scanf ("%d", &n);p riority_queue<int,vector<int>,greater<int> > Que;memset (d,0,sizeof (d) ); memset (vis,0,sizeof (VIS)); int ans = 0,num = 0;for (int i = 1;i <= n;i++) {scanf ("%d", &a[i]); if (a[i] = = i) {num++;} D[a[i]] + +;} for (int i = 1;i <= n;i++) {if (d[i] = = 0) {Que.push (i);}} while (!que.empty ()) {int p = que.top (); Que.pop (); ans + = 1;vis[p] = 1;if (Vis[a[p]]) {num + = 1;continue;} D[A[A[P]] [--;vis[a[p]] = 1;if (D[a[a[p]] = = 0) {Que.push (P);} num + = 2;} Ans + = (n-num)/2;printf ("%d\n", ans);} return 0;}

Henan 2014 provincial Race world's gateway topological sorting