Submission #1115821

#	Time	Username	Problem	Language	Result	Execution time	Memory
1115821		vjudge1	Cat in a tree (BOI17_catinatree)	C++17	100 / 100	94 ms	22188 KiB

catinatree

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
vector<int> g[200005];
int d;
pair<int, int> f[200005];
void dfs(int x) {
    if (g[x].size() == 0) {
        f[x] = {1, 0};
        return;
    }
    int c = 0;
    vector<int> v;
    for (int w : g[x]) {
        dfs(w);
        c += f[w].first;
        v.push_back(f[w].second + 1);
    }
    sort(v.begin(), v.end());
    int j = -1;
    for (int i = 0; i < v.size() - 1; i++) {
        if (v[i] + v[i + 1] < d) {
            c--;
        }
        else {
            j = i;
            break;
        }
    }
    if (j == -1) j = v.size() - 1;
    if (v[j] >= d) {
        v[j] = 0;
        c++;
    }
    f[x] = {c, v[j]};
    /*cout << x << " " << f[x].first << " " << j << " " << v[j] << '\n';
    for (int w : v) cout << w << " ";
    cout << '\n';*/
}
int main() {
    int n;
    cin >> n >> d;
    for (int i = 1; i < n; i++) {
        int x;
        cin >> x;
        g[x].push_back(i);
    }
    dfs(0);
    cout << f[0].first;
}

Compilation message (stderr)

catinatree.cpp: In function 'void dfs(int)':
catinatree.cpp:22:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 |     for (int i = 0; i < v.size() - 1; i++) {
      |                     ~~^~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 40 / 40
• Subtask 3: 49 / 49