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답안 #1059343

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
1059343 2024-08-14T21:31:20 Z Zicrus Islands (IOI08_islands) C++17
90 / 100
 905 ms 131072 KB 
#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
 
int n;
vector<vector<pair<int, int>>> adj; // length, node
vector<bool> vst;
vector<int> comps;
vector<bool> cyc;
vector<pair<int, int>> nxt; // length, node
vector<int> globToCyc;
 
int cycRoot;
ll dfsCyc(int &cur, int &par) {
    vst[cur] = true;
    {
        vector<pair<int, int>> numE;
        for (auto &e : adj[cur]) {
            if (e.second == par) {
                numE.push_back(e);
            }
        }
        if (numE.size() == 2) {
            vst[numE[0].second] = true;
            cyc[cur] = cyc[numE[0].second] = true;
            cycRoot = cur;
            nxt[cur] = numE[0];
            nxt[numE[0].second] = {numE[1].first, cur};
            return -1;
        }
    }
    for (auto &e : adj[cur]) {
        if (e.second == par) continue;
        if (vst[e.second] && !cyc[e.second]) {
            cyc[cur] = true;
            nxt[cur] = e;
            cycRoot = e.second;
            return e.second;
        }
        else {
            ll val = dfsCyc(e.second, cur);
            if (val == -1) continue;
            cyc[cur] = true;
            nxt[cur] = e;
            return cur == val ? -1 : val;
        }
    }
    return -1;
}
 
ll mxLen = 0;
ll dfsTreeSz(int &cur, int &par) {
    ll mx = 0;
    ll nxtMx = 0;
    for (auto &e : adj[cur]) {
        if (e.second == par) continue;
        if (cyc[e.second]) continue;
        ll val = e.first + dfsTreeSz(e.second, cur);
        if (val > mx) {
            nxtMx = mx;
            mx = val;
        }
        else if (val > nxtMx) {
            nxtMx = val;
        }
    }
    mxLen = max(mxLen, nxtMx + mx);
    return mx;
}
 
ll solveComp(int &root) {
    mxLen = 0;
    int minusOne = -1;
    dfsCyc(root, minusOne);
    ll totLen = 0;
    int x = cycRoot;
    vector<int> cycle;
    do {
        globToCyc[x] = cycle.size();
        cycle.push_back(x);
        totLen += nxt[x].first;
        x = nxt[x].second;
    } while (x != cycRoot);
    vector<ll> treeSz(cycle.size());
    for (int i = 0; i < cycle.size(); i++) {
        treeSz[i] = dfsTreeSz(cycle[i], minusOne);
    }
    ll res = mxLen;
    int mxId = cycle[0];
    ll mxVal = treeSz[0];
    ll lenSum = 0;
    int cur = cycle[0];
    for (int i = 0; i < cycle.size(); i++) {
        if (cur == cycle[i] || mxId == i) {
            cur = cycle[i];
            lenSum = nxt[cur].first;
            cur = nxt[cur].second;
            mxId = globToCyc[cur];
            mxVal = lenSum + treeSz[globToCyc[cur]];
        }
        while (cur != cycle[i]) {
            ll val = lenSum + treeSz[globToCyc[cur]];
            if (val >= mxVal) {
                mxVal = val;
                mxId = globToCyc[cur];
            }
            lenSum += nxt[cur].first;
            cur = nxt[cur].second;
        }
        res = max(res, treeSz[i] + mxVal);
        lenSum -= nxt[cycle[i]].first;
        mxVal -= nxt[cycle[i]].first;
    }
    return res;
}
 
void dfs1(int &cur) {
    vst[cur] = true;
    for (auto &e : adj[cur]) {
        if (vst[e.second]) continue;
        dfs1(e.second);
    }
}
 
int main() {
    cin >> n;
    adj = vector<vector<pair<int, int>>>(n);
    cyc = vector<bool>(n);
    nxt = vector<pair<int, int>>(n);
    globToCyc = vector<int>(n);
    for (int i = 0; i < n; i++) {
        ll a, l;
        cin >> a >> l;
        adj[i].push_back({l, a-1});
        adj[a-1].push_back({l, i});
    }
    vst = vector<bool>(n);
    for (int i = 0; i < n; i++) {
        if (vst[i]) continue;
        dfs1(i);
        comps.push_back(i);
    }
    vst = vector<bool>(n);
 
    ll res = 0;
    for (auto &e : comps) {
        res += solveComp(e);
    }
    cout << res;
}

Compilation message

islands.cpp: In function 'll solveComp(int&)':
islands.cpp:86:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   86 |     for (int i = 0; i < cycle.size(); i++) {
      |                     ~~^~~~~~~~~~~~~~
islands.cpp:94:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   94 |     for (int i = 0; i < cycle.size(); i++) {
      |                     ~~^~~~~~~~~~~~~~

Subtask #1
33.0 / 33.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 348 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 1 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 0 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 360 KB Output is correct

Subtask #2
3.0 / 3.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 348 KB Output is correct
2 Correct 1 ms 348 KB Output is correct

Subtask #3
4.0 / 4.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 348 KB Output is correct
2 Correct 2 ms 860 KB Output is correct

Subtask #4
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 8 ms 1628 KB Output is correct
2 Correct 15 ms 4352 KB Output is correct
3 Correct 11 ms 1884 KB Output is correct
4 Correct 5 ms 1104 KB Output is correct

Subtask #5
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 27 ms 5980 KB Output is correct
2 Correct 43 ms 9220 KB Output is correct

Subtask #6
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 75 ms 16724 KB Output is correct
2 Correct 81 ms 23028 KB Output is correct
3 Correct 113 ms 32216 KB Output is correct

Subtask #7
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 154 ms 30320 KB Output is correct
2 Correct 231 ms 55236 KB Output is correct
3 Correct 204 ms 64856 KB Output is correct
4 Correct 293 ms 89176 KB Output is correct

Subtask #8
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 431 ms 74928 KB Output is correct
2 Correct 715 ms 131072 KB Output is correct
3 Correct 307 ms 70316 KB Output is correct
4 Correct 394 ms 112976 KB Output is correct
5 Correct 390 ms 113160 KB Output is correct
6 Correct 905 ms 84540 KB Output is correct
7 Correct 447 ms 131072 KB Output is correct

Subtask #9
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 432 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -