Submission #639113

# Submission time Handle Problem Language Result Execution time Memory
639113 2022-09-08T15:34:57 Z puppy Islands (IOI08_islands) C++17
80 / 100
691 ms 131072 KB
#include <bits/stdc++.h>
using namespace std;
int N;
vector<pair<int, int>> adj[1000005];
bitset<1000005> visited;
bitset<1000005> cycle;
pair<int, int> parent[1000005];
int cyc, cyc2;
int cycval;
long long dp[1000005];
vector<int> vc;

void dfs(const int &v, const int &p, const int &asg)
{
    visited[v] = true;
    parent[v] = make_pair(p, asg);
    int cnt = 0;
    int tmp;
    for(auto &i:adj[v]){
        if(i.first==p){
            ++cnt;
            if(cnt==1) tmp = i.second;
            else{
                if(cyc == -1){
                    cyc = v;
                    cyc2 = i.first;
                    cycle[v] = true;
                    cycval = (tmp == asg) ? i.second : tmp;
                }
            }
            continue;
        }
        if(visited[i.first]){
            if(cyc == -1){
                cyc = v;
                cyc2 = i.first;
                cycval = i.second;
                cycle[v] = true;
            }
            continue;
        }
        dfs(i.first, v, i.second);
    }
}
int par;
void treedfs(int v, int prv)
{
    vc.push_back(v);
    for(auto &i:adj[v]){
        if(i.first == prv || cycle[i.first]) continue;
        dp[i.first] = dp[v] + i.second;
        treedfs(i.first, v);
    }
}
void treedfs2(int v, int prv)
{
    for(auto &i:adj[v]){
        if(cycle[i.first] && i.first != par) continue;
        if(i.first == prv) continue;
        dp[i.first] = dp[v] + i.second;
        treedfs2(i.first, v);
    }
}
int main()
{
    ios::sync_with_stdio(false); cin.tie(0);
    long long ans = 0;
    cin>>N;
    int tmp, k;
    for(int i=1;i<=N;i++){
        cin>>tmp>>k;
        adj[tmp].push_back(make_pair(i, k));
        adj[i].push_back(make_pair(tmp, k));
    }
    for(int i=0;i<1000005;i++) adj[i].shrink_to_fit();
    int cycstart, cycend, tt;
    long long cur, dsp, sub;
    long long backup;
    long long m; int loc;
    vector<int> fun, val;
    for(int i=1;i<=N;i++){
        if(visited[i]) continue;
        long long tmpans = 0;
        vector<int>().swap(fun);
        vector<int>().swap(val);
        cyc = -1;
        cyc2 = -1;
        dfs(i, 0, 0);
        cycstart = cyc;
        cycend = cyc2;
        fun.push_back(cycstart);
        val.push_back(cycval);
        while(cycstart != cycend){
            tt = parent[cycstart].second;
            cycstart = parent[cycstart].first;
            cycle[cycstart] = true;
            fun.push_back(cycstart);
            val.push_back(tt);
        }
        fun.shrink_to_fit();
        val.shrink_to_fit();
        for(int i:fun){
            par = i;
            vector<int>().swap(vc);
            treedfs(i, i);
            vc.shrink_to_fit();
            m = -1;
            for(int k:vc){
                if(dp[k] > m){
                    m = dp[k];
                    loc = k;
                }
            }
            backup = m;
            dp[loc] = 0;
            treedfs2(loc, loc);
            m = -1;
            for(int k:vc) m = max(m, dp[k]);
            tmpans = max(tmpans, m);
            dp[i] = backup;
        }
        multiset<long long> heap;
        cur = dsp = sub = 0;
        for(int i=1;i<(int)fun.size();i++){
            cur += val[i];
            heap.insert(cur+dp[fun[i]]);
        }
        tmpans = max(tmpans, *--heap.end()+dp[fun[0]]);
        for(int i=1;i<(int)fun.size();i++){
            dsp += val[i];
            heap.erase(heap.find(dsp + dp[fun[i]]));
            sub += val[i];
            cur += val[i-1];
            heap.insert(cur+dp[fun[i-1]]);
            tmpans = max(tmpans, *--heap.end()+dp[fun[i]]-sub);
        }
        heap.clear();
        cur = dsp = sub = 0;
        for(int i=(int)fun.size()-2;i>=0;i--){
            cur += val[i+1];
            heap.insert(cur+dp[fun[i]]);
        }
        tmpans = max(tmpans, *--heap.end()+dp[fun.back()]);
        for(int i=(int)fun.size()-2;i>=0;i--){
            sub += val[i+1];
            dsp += val[i+1];
            cur += val[(i+2)%val.size()];
            heap.erase(heap.find(dsp+dp[fun[i]]));
            heap.insert(cur+dp[fun[(i+1)%fun.size()]]);
            tmpans = max(tmpans, *--heap.end() + dp[fun[i]]-sub);
        }
        ans += tmpans;
    }
    cout<<ans<<'\n';
}

Compilation message

islands.cpp: In function 'void dfs(const int&, const int&, const int&)':
islands.cpp:28:28: warning: 'tmp' may be used uninitialized in this function [-Wmaybe-uninitialized]
   28 |                     cycval = (tmp == asg) ? i.second : tmp;
      |                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
islands.cpp: In function 'int main()':
islands.cpp:116:21: warning: 'loc' may be used uninitialized in this function [-Wmaybe-uninitialized]
  116 |             treedfs2(loc, loc);
      |             ~~~~~~~~^~~~~~~~~~
# Verdict Execution time Memory Grader output
1 Correct 14 ms 23764 KB Output is correct
2 Correct 15 ms 23764 KB Output is correct
3 Correct 14 ms 23892 KB Output is correct
4 Correct 14 ms 23764 KB Output is correct
5 Correct 14 ms 23764 KB Output is correct
6 Correct 14 ms 23764 KB Output is correct
7 Correct 13 ms 23764 KB Output is correct
8 Correct 14 ms 23764 KB Output is correct
9 Correct 14 ms 23772 KB Output is correct
10 Correct 13 ms 23764 KB Output is correct
11 Correct 15 ms 23764 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 14 ms 23892 KB Output is correct
2 Correct 15 ms 23860 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 15 ms 23956 KB Output is correct
2 Correct 18 ms 24276 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 23 ms 24788 KB Output is correct
2 Correct 40 ms 27604 KB Output is correct
3 Correct 26 ms 25160 KB Output is correct
4 Correct 17 ms 24448 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 49 ms 29008 KB Output is correct
2 Correct 78 ms 30844 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 105 ms 36708 KB Output is correct
2 Correct 199 ms 44788 KB Output is correct
3 Correct 243 ms 56868 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 242 ms 46092 KB Output is correct
2 Correct 333 ms 76900 KB Output is correct
3 Correct 671 ms 86852 KB Output is correct
4 Correct 687 ms 118588 KB Output is correct
# Verdict Execution time Memory Grader output
1 Correct 282 ms 86628 KB Output is correct
2 Runtime error 691 ms 131072 KB Execution killed with signal 9
3 Halted 0 ms 0 KB -
# Verdict Execution time Memory Grader output
1 Runtime error 309 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -