Submission #920588

#	Time	Username	Problem	Language	Result	Execution time	Memory
920588		boyliguanhan	Islands (IOI08_islands)	C++17	100 / 100	246 ms	52196 KiB

islands

#include<bits/stdc++.h>
using namespace std;
#define N 1000100
#define ll long long
int deg[N];
#define ck(a,b) a=max(a,b)
#define Ck(a,b,c) a=max({a,b,c})
ll v[N], l[N], O[N], I[N];
ll solve(int x) {
    ll mx1=O[x],mx2=O[x],sum=l[x],ans1=I[x],ans2=-1e18;
    for(int y=v[x];y-x;sum+=l[y],deg[y]=0,y=v[y]) {
        Ck(ans1,O[y]+sum+mx1,I[y]);
        ck(ans2,O[y]-sum+mx2);
        ck(mx1,O[y]-sum);
        ck(mx2,O[y]+sum);
    }
    return max(ans1,ans2+sum);
}
int main() {
    cin.sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>v[i]>>l[i],deg[v[i]]++;
    queue<int> q;
    for(int i=1;i<=n;i++)
        if(!deg[i])q.push(i);
    while (q.size()) {
        int x=q.front(),y=v[x];
        q.pop();
        Ck(I[y],O[y]+O[x]+l[x],I[x]);
        ck(O[y],O[x]+l[x]);
        if(!--deg[y])q.push(y);
    }
    ll ans=0;
    for(int i=1;i<=n;i++)
        if(deg[i])
            ans+=solve(i),deg[i]=0;
    cout<<ans;
}

• Subtask 1: 33 / 33
• Subtask 2: 3 / 3
• Subtask 3: 4 / 4
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10