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Submission #468208

# Submission time Handle Problem Language Result Execution time Memory
468208 2021-08-27T06:45:39 Z idk321 Mousetrap (CEOI17_mousetrap) C++17
100 / 100
 935 ms 272200 KB 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

const int N = 1000005;
vector<int> adj[N];
int upCost[N];
int downCost[N];
int p[N];
vector<vector<int>> sideNodes;

int n, t, m;

bool comp(int a, int b) {
    return downCost[a] < downCost[b];
}

void dfs(int node, int par) {
    p[node] = par;
    for (int next : adj[node]) {
        if (next == par) continue;
        dfs(next, node);
    }
}

void calcDown(int node, int depth) {
    if (adj[node].size() == 1) {
        downCost[node] = depth;
        return;
    }
    if (adj[node].size() == 2) {
        downCost[node] = depth + 1;
        return;
    }

    array<int, 2> most{0, 0};
    for (int next : adj[node]) {
        if (next == p[node]) continue;
        calcDown(next, depth + 1);
        if (downCost[next] > most[1]) most[1] = downCost[next];
        if (most[0] < most[1]) swap(most[0], most[1]);
    }

    downCost[node] = adj[node].size() - 2 + most[1];
}

void goUp(int node, int prev = -1) {
    if (node == t) return;
    goUp(p[node], node);
    upCost[node] += upCost[p[node]];
    if (p[node] != t) {
        upCost[node] += adj[p[node]].size();
        upCost[node] -= 2;
    }
    vector<int> curSideNodes;
    for (int next : adj[node]) {
        if (next == prev || next == p[node]) continue;
        curSideNodes.push_back(next);
        upCost[next] = upCost[node];
        calcDown(next, 1);
    }
    sort(curSideNodes.rbegin(), curSideNodes.rend(), comp);
    sideNodes.push_back(curSideNodes);
}



bool poss(int most) {
    int already = 0;
    int canHave = 1;
    for (auto it = sideNodes.rbegin(); it != sideNodes.rend(); it++) {
        vector<int>& nodesVector = *it;
        int blocked = 0;
        for (int i : nodesVector) {
            if (already + downCost[i] + upCost[i] + nodesVector.size() - blocked - 1 > most) {
                if (already < canHave) {
                    already++;
                    blocked++;
                } else return false;
            }
        }
        canHave++;
    }

    return already <= most;
}


int bs() {
    int a = 0;
    int b = 2 * n;
    int res = -1;
    while (a <= b) {

        int mid =(a +b ) / 2;
        //cout << a<< " " << b << " "<< mid << " " << poss(mid) << "\n";
        if (poss(mid)) {
            res = mid;
            b = mid - 1;
        } else a = mid + 1;
    }

    return res;
}

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

    cin >> n >> t >> m;

    for (int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    dfs(t, -1);
    goUp(m);

    /*
    for (int i = 1; i <= n; i++ )cout << upCost[i] << " ";
    cout << "\n";
    for (int i = 1; i <= n; i++ )cout << downCost[i] << " ";
    cout << "\n"; */
    cout << bs() << "\n";
}

/*
10 1 4
1 2
2 3
2 4
3 9
3 5
4 7
4 6
6 8
7 10
*/

Compilation message

mousetrap.cpp: In function 'bool poss(int)':
mousetrap.cpp:76:86: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   76 |             if (already + downCost[i] + upCost[i] + nodesVector.size() - blocked - 1 > most) {
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 23756 KB Output is correct
2 Correct 14 ms 23700 KB Output is correct
3 Correct 14 ms 23804 KB Output is correct
4 Correct 14 ms 23764 KB Output is correct
5 Correct 14 ms 23756 KB Output is correct
6 Correct 15 ms 23756 KB Output is correct
7 Correct 15 ms 23716 KB Output is correct
8 Correct 14 ms 23764 KB Output is correct
9 Correct 14 ms 23800 KB Output is correct
10 Correct 14 ms 23756 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 357 ms 62980 KB Output is correct
2 Correct 325 ms 59020 KB Output is correct
3 Correct 843 ms 64000 KB Output is correct
4 Correct 411 ms 44048 KB Output is correct
5 Correct 867 ms 64000 KB Output is correct
6 Correct 859 ms 63952 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 23756 KB Output is correct
2 Correct 14 ms 23700 KB Output is correct
3 Correct 14 ms 23804 KB Output is correct
4 Correct 14 ms 23764 KB Output is correct
5 Correct 14 ms 23756 KB Output is correct
6 Correct 15 ms 23756 KB Output is correct
7 Correct 15 ms 23716 KB Output is correct
8 Correct 14 ms 23764 KB Output is correct
9 Correct 14 ms 23800 KB Output is correct
10 Correct 14 ms 23756 KB Output is correct
11 Correct 15 ms 23744 KB Output is correct
12 Correct 14 ms 23804 KB Output is correct
13 Correct 14 ms 23756 KB Output is correct
14 Correct 16 ms 24060 KB Output is correct
15 Correct 14 ms 23932 KB Output is correct
16 Correct 15 ms 23756 KB Output is correct
17 Correct 14 ms 23756 KB Output is correct
18 Correct 15 ms 23840 KB Output is correct
19 Correct 15 ms 23888 KB Output is correct
20 Correct 14 ms 23800 KB Output is correct
21 Correct 14 ms 23884 KB Output is correct
22 Correct 15 ms 23856 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 23756 KB Output is correct
2 Correct 14 ms 23700 KB Output is correct
3 Correct 14 ms 23804 KB Output is correct
4 Correct 14 ms 23764 KB Output is correct
5 Correct 14 ms 23756 KB Output is correct
6 Correct 15 ms 23756 KB Output is correct
7 Correct 15 ms 23716 KB Output is correct
8 Correct 14 ms 23764 KB Output is correct
9 Correct 14 ms 23800 KB Output is correct
10 Correct 14 ms 23756 KB Output is correct
11 Correct 357 ms 62980 KB Output is correct
12 Correct 325 ms 59020 KB Output is correct
13 Correct 843 ms 64000 KB Output is correct
14 Correct 411 ms 44048 KB Output is correct
15 Correct 867 ms 64000 KB Output is correct
16 Correct 859 ms 63952 KB Output is correct
17 Correct 15 ms 23744 KB Output is correct
18 Correct 14 ms 23804 KB Output is correct
19 Correct 14 ms 23756 KB Output is correct
20 Correct 16 ms 24060 KB Output is correct
21 Correct 14 ms 23932 KB Output is correct
22 Correct 15 ms 23756 KB Output is correct
23 Correct 14 ms 23756 KB Output is correct
24 Correct 15 ms 23840 KB Output is correct
25 Correct 15 ms 23888 KB Output is correct
26 Correct 14 ms 23800 KB Output is correct
27 Correct 14 ms 23884 KB Output is correct
28 Correct 15 ms 23856 KB Output is correct
29 Correct 14 ms 23724 KB Output is correct
30 Correct 362 ms 76204 KB Output is correct
31 Correct 356 ms 76256 KB Output is correct
32 Correct 543 ms 272200 KB Output is correct
33 Correct 408 ms 96836 KB Output is correct
34 Correct 861 ms 77428 KB Output is correct
35 Correct 866 ms 77416 KB Output is correct
36 Correct 914 ms 103100 KB Output is correct
37 Correct 935 ms 103032 KB Output is correct
38 Correct 684 ms 101940 KB Output is correct
39 Correct 749 ms 101864 KB Output is correct
40 Correct 758 ms 101944 KB Output is correct