33 lines
663 B
C++
33 lines
663 B
C++
// lanqiao 182 小朋友崇拜圈
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#include<bits/stdc++.h>
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using namespace std;
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const int N = 1e5 + 10;
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int n, a[N], dfn[N], idx, mindfn;
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int dfs(int x){
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dfn[x] = ++idx;
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if(dfn[a[x]]){
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if(dfn[a[x]] >= mindfn) return dfn[x] - dfn[a[x]] + 1;
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return 0;
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}
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return dfs(a[x]);
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}
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int main(){
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ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
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cin >> n;
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for(int i = 1; i <= n; i++) cin >> a[i];
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int ans = 0;
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for(int i = 1; i <= n; i++){
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if(!dfn[i]){
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mindfn = idx + 1;
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ans = max(ans, dfs(i));
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}
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}
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cout << ans << endl;
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return 0;
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}
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/* test samples
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9
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3 4 2 5 3 8 4 6 9
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*/ |