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답안 #114710

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
114710 2019-06-02T12:18:45 Z zubec Islands (IOI08_islands) C++14
64 / 100
 425 ms 131072 KB 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;

const int N = 1000100;

int n;

ll ans = 0;

int len[N];

vector <pair<int, int> > g[N];

bool used[N], inCycle[N];

int used2[N], pr[N], cEnd, cStrt, pr2[N];

int cId;

int fnd_cycle(int v, int p){
    used2[v] = 1;

    for (int i = 0; i < g[v].size(); i++){
        int to = g[v][i].first, id = g[v][i].second;
        if (id == p)
            continue;
        if (used2[to] == 0){
            pr[to] = v;
            pr2[to] = id;
            if (fnd_cycle(to, id)){
                return 1;
            }
        } else
        if (used2[to] == 1){
            cEnd = v;
            cId = id;
            cStrt = to;
            return 1;
        }
    }

    used2[v] = 2;

    return 0;
}

ll dfs(int v, int p){
    used[v] = 1;
    ll curmx = 0;
    for (int i = 0; i < g[v].size(); i++){
        int to = g[v][i].first;
        if (to == p)
            continue;
        curmx = max(curmx, dfs(to, v)+len[g[v][i].second]);
    }
    return curmx;
}

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);

    cin >> n;
    for (int i = 1; i <= n; i++){
        int to;
        cin >> to >> len[i];
        g[i].push_back({to, i});
        g[to].push_back({i, i});
    }
    for (int i = 1; i <= n; i++){
        if (used[i])
            continue;

        fnd_cycle(i, 0);

        vector <int> cycle;
        vector <ll> lens;
        cycle.push_back(cStrt);
        lens.push_back(0);
        lens.push_back(len[cId]);
        for (int v = cEnd; v != cStrt; v = pr[v]){
            cId = pr2[v];
            cycle.push_back(v);
            lens.push_back(len[cId]);
        }
        for (int j = 0; j < cycle.size(); j++){
            inCycle[cycle[j]] = 1;
        }
        for (int j = 1; j < lens.size(); j++){
            lens[j] += lens[j-1];
        }

        ll curans = 0;

        ll mx1 = -1e18, mx2 = -1e18;

        for (int j = 0; j < cycle.size(); j++){
            int v = cycle[j];
            used[v] = 1;

            ll curmx = 0;
            for (int j = 0; j < g[v].size(); j++){
                int to = g[v][j].first;
                if (inCycle[to])
                    continue;
                curmx = max(curmx, dfs(to, v)+len[g[v][j].second]);
            }

            curans = max(curans, curmx);

            if (j == 0){

                mx1 = max(mx1, curmx);
                mx2 = max(mx2, curmx);

            } else {

                curans = max(curans, curmx+lens[j] + mx1 );
                curans = max(curans, curmx+lens.back()-lens[j] + mx2 );

                mx1 = max(mx1, curmx-lens[j]);
                mx2 = max(mx2, curmx+lens[j]);

            }

        }

        ans += curans;

    }
    cout << ans;


}

Compilation message

islands.cpp: In function 'int fnd_cycle(int, int)':
islands.cpp:25:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < g[v].size(); i++){
                     ~~^~~~~~~~~~~~~
islands.cpp: In function 'll dfs(int, int)':
islands.cpp:52:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < g[v].size(); i++){
                     ~~^~~~~~~~~~~~~
islands.cpp: In function 'int main()':
islands.cpp:87:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0; j < cycle.size(); j++){
                         ~~^~~~~~~~~~~~~~
islands.cpp:90:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 1; j < lens.size(); j++){
                         ~~^~~~~~~~~~~~~
islands.cpp:98:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int j = 0; j < cycle.size(); j++){
                         ~~^~~~~~~~~~~~~~
islands.cpp:103:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for (int j = 0; j < g[v].size(); j++){
                             ~~^~~~~~~~~~~~~

Subtask #1
27.0 / 33.0

# 결과 실행 시간 메모리 Grader output
1 Correct 22 ms 23800 KB Output is correct
2 Incorrect 21 ms 23936 KB Output isn't correct
3 Correct 22 ms 23936 KB Output is correct
4 Correct 22 ms 23936 KB Output is correct
5 Correct 21 ms 23808 KB Output is correct
6 Correct 20 ms 23928 KB Output is correct
7 Correct 20 ms 23808 KB Output is correct
8 Correct 21 ms 23936 KB Output is correct
9 Correct 20 ms 23808 KB Output is correct
10 Incorrect 21 ms 23928 KB Output isn't correct
11 Correct 21 ms 23936 KB Output is correct

Subtask #2
3.0 / 3.0

# 결과 실행 시간 메모리 Grader output
1 Correct 21 ms 23928 KB Output is correct
2 Correct 21 ms 23928 KB Output is correct

Subtask #3
4.0 / 4.0

# 결과 실행 시간 메모리 Grader output
1 Correct 21 ms 23936 KB Output is correct
2 Correct 23 ms 24320 KB Output is correct

Subtask #4
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 29 ms 24896 KB Output is correct
2 Correct 43 ms 27180 KB Output is correct
3 Correct 33 ms 25336 KB Output is correct
4 Incorrect 29 ms 24576 KB Output isn't correct

Subtask #5
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 58 ms 28024 KB Output is correct
2 Correct 56 ms 30380 KB Output is correct

Subtask #6
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 102 ms 36084 KB Output is correct
2 Correct 104 ms 39472 KB Output is correct
3 Correct 128 ms 47448 KB Output is correct

Subtask #7
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 157 ms 46032 KB Output is correct
2 Correct 221 ms 64364 KB Output is correct
3 Correct 232 ms 69220 KB Output is correct
4 Correct 286 ms 84192 KB Output is correct

Subtask #8
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 331 ms 75876 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 425 ms 131072 KB Execution killed with signal 9 (could be triggered by violating memory limits)
2 Halted 0 ms 0 KB -