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답안 #555553

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
555553 2022-05-01T07:38:23 Z alextodoran Islands (IOI08_islands) C++17
90 / 100
 1110 ms 131072 KB 
/**
 ____ ____ ____ ____ ____
||a |||t |||o |||d |||o ||
||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|

**/

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N_MAX = 1000000;

int N;
struct Edge {
    int to;
    int len;
};
vector <Edge> adj[N_MAX + 2];

Edge par[N_MAX + 2];
int depth[N_MAX + 2];

tuple <int, int, int> backEdge;

int curr[N_MAX + 2];
void dfs (int u) {
    depth[u] = 0;
    while (u != 0) {
        if (curr[u] < (int) adj[u].size()) {
            Edge e = adj[u][curr[u]++];
            if (depth[e.to] == -1) {
                par[e.to] = Edge{u, e.len};
                depth[e.to] = depth[u] + 1;
                u = e.to;
            } else if (depth[e.to] > depth[u]) {
                backEdge = make_tuple(u, e.to, e.len);
            }
        } else {
            u = par[u].to;
        }
    }
}

bitset <N_MAX + 2> root;

ll maxAny[N_MAX + 2];
ll maxDown[N_MAX + 2];

queue <int> q;
vector <int> order;
vector <ll> maxDowns;
void compute (int s) {
    q.push(s);
    depth[s] = 0;
    while (q.empty() == false) {
        int u = q.front(); q.pop();
        order.push_back(u);
        for (Edge e : adj[u]) {
            if (depth[e.to] == -1 && root[e.to] == false) {
                q.push(e.to);
                depth[e.to] = depth[u] + 1;
            }
        }
    }
    reverse(order.begin(), order.end());
    for (int u : order) {
        for (Edge e : adj[u]) {
            if (depth[u] < depth[e.to] && root[e.to] == false) {
                maxAny[u] = max(maxAny[u], maxAny[e.to]);
                maxDown[u] = max(maxDown[u], maxDown[e.to] + e.len);
                maxDowns.push_back(maxDown[e.to] + e.len);
            }
        }
        sort(maxDowns.begin(), maxDowns.end(), greater <ll> ());
        if ((int) maxDowns.size() >= 2) {
            maxAny[u] = max(maxAny[u], maxDowns[0] + maxDowns[1]);
        }
        maxAny[u] = max(maxAny[u], maxDown[u]);
        maxDowns.clear();
    }
    order.clear();
}

int roots[N_MAX + 2];
int group[N_MAX + 2];
int cntRoots;
int cntGroups;

multiset <ll> s;

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

    cin >> N;
    for (int u = 1; u <= N; u++) {
        Edge e;
        cin >> e.to >> e.len;
        assert(u != e.to);
        adj[u].push_back(Edge{e.to, e.len});
        adj[e.to].push_back(Edge{u, e.len});
    }

    fill(depth + 1, depth + N + 1, -1);
    for (int u = 1; u <= N; u++) {
        if (depth[u] == -1) {
            dfs(u);
            int v1, v2, len; tie(v1, v2, len) = backEdge;
            swap(v1, v2);
            par[v2] = Edge{v1, len};
            cntGroups++;
            int v = v1;
            while (v != v2) {
                root[v] = true;
                roots[++cntRoots] = v;
                group[cntRoots] = cntGroups;
                v = par[v].to;
            }
            root[v] = true;
            roots[++cntRoots] = v;
            group[cntRoots] = cntGroups;
        }
    }

    fill(depth + 1, depth + N + 1, -1);
    for (int u = 1; u <= N; u++) {
        if (root[u] == true) {
            compute(u);
        }
    }

    ll answer = 0;
    for (int g = 1, i = 1; g <= cntGroups; g++) {
        int j = i;
        while (j < cntRoots && group[j + 1] == g) {
            j++;
        }
        ll totalLen = 0;
        ll maxLen = 0;
        for (int k = i; k <= j; k++) {
            int u = roots[k];
            totalLen += par[u].len;
            maxLen = max(maxLen, maxAny[u]);
        }

        ll len = 0;
        for (int k = j; k > i; k--) {
            int u = roots[k];
            len += par[u].len;
            s.insert(maxDown[u] + len);
        }
        ll lazy = 0;

        for (int k = i, u = roots[i]; k <= j; k++) {
            assert(s.empty() == false);
            maxLen = max(maxLen, *s.rbegin() + lazy + maxDown[u]);
            s.insert(maxDown[u] - lazy);
            lazy += par[u].len;
            u = par[u].to;
            assert(s.find((maxDown[u] + totalLen) - lazy) != s.end());
            s.erase(s.find((maxDown[u] + totalLen) - lazy));
        }
        answer += maxLen;
        s.clear();
        i = j + 1;
    }
    cout << answer << "\n";

    return 0;
}

Subtask #1
33.0 / 33.0

# 결과 실행 시간 메모리 Grader output
1 Correct 12 ms 23764 KB Output is correct
2 Correct 16 ms 23852 KB Output is correct
3 Correct 13 ms 23848 KB Output is correct
4 Correct 13 ms 23856 KB Output is correct
5 Correct 14 ms 23764 KB Output is correct
6 Correct 14 ms 23824 KB Output is correct
7 Correct 13 ms 23824 KB Output is correct
8 Correct 12 ms 23856 KB Output is correct
9 Correct 12 ms 23764 KB Output is correct
10 Correct 14 ms 23880 KB Output is correct
11 Correct 13 ms 23764 KB Output is correct

Subtask #2
3.0 / 3.0

# 결과 실행 시간 메모리 Grader output
1 Correct 15 ms 23964 KB Output is correct
2 Correct 17 ms 23960 KB Output is correct

Subtask #3
4.0 / 4.0

# 결과 실행 시간 메모리 Grader output
1 Correct 15 ms 23960 KB Output is correct
2 Correct 17 ms 24252 KB Output is correct

Subtask #4
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 20 ms 25044 KB Output is correct
2 Correct 31 ms 27060 KB Output is correct
3 Correct 24 ms 25340 KB Output is correct
4 Correct 17 ms 24532 KB Output is correct

Subtask #5
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 40 ms 28396 KB Output is correct
2 Correct 61 ms 31560 KB Output is correct

Subtask #6
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 93 ms 38516 KB Output is correct
2 Correct 156 ms 42128 KB Output is correct
3 Correct 168 ms 49332 KB Output is correct

Subtask #7
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 184 ms 52212 KB Output is correct
2 Correct 257 ms 69464 KB Output is correct
3 Correct 422 ms 73940 KB Output is correct
4 Correct 467 ms 88908 KB Output is correct

Subtask #8
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 373 ms 110624 KB Output is correct
2 Correct 944 ms 116140 KB Output is correct
3 Correct 378 ms 81124 KB Output is correct
4 Correct 462 ms 109736 KB Output is correct
5 Correct 494 ms 110376 KB Output is correct
6 Correct 1110 ms 91608 KB Output is correct
7 Correct 791 ms 125284 KB Output is correct

Subtask #9
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 336 ms 90412 KB Output is correct
2 Correct 360 ms 90476 KB Output is correct
3 Runtime error 617 ms 131072 KB Execution killed with signal 9
4 Halted 0 ms 0 KB -