Submission #56069

#	Time	Username	Problem	Language	Result	Execution time	Memory
56069		gabrielsimoes	Mousetrap (CEOI17_mousetrap)	C++17	0 / 100	51 ms	13024 KiB

mousetrap

#include <bits/stdc++.h>
using namespace std;

typedef pair<int,int> pii;

const int MAXN = 1e5+10, MAXL = 18;

int n, t, s;
vector<int> g[MAXN];
bool good[MAXN];

void dfs0(int cur, int pre) {
    for (int nx : g[cur]) {
        if (nx != pre) {
            dfs0(nx, cur);
            good[cur] |= good[nx];
        }
    }
}

int ans[MAXN];
void dfs1(int cur, int pre) {
    if (cur == t) return;

    int ansGood = -1;
    vector<int> v;

    for (int nx : g[cur]) {
        if (nx != pre) {
            dfs1(nx, cur);

            if (good[nx]) ansGood = ans[nx];
            else v.push_back(ans[nx]);
        }
    }

    sort(v.rbegin(), v.rend());

    int &ret = ans[cur];

    for (int i = 0; i < v.size(); i++) {
        if (i % 2) ret += v[i];
        else ret++;
    }

    if (!good[cur]) ret++;
    else ret += ansGood;
}

int main() {
    scanf("%d %d %d", &n, &t, &s);
    for (int i = 1,a,b; i < n; i++) {
        scanf("%d %d", &a, &b);
        g[a].push_back(b);
        g[b].push_back(a);
    }

    good[t] = true;
    dfs0(s, s);
    dfs1(s, s);

    printf("%d\n", ans[s]);
}

Compilation message (stderr)

mousetrap.cpp: In function 'void dfs1(int, int)':
mousetrap.cpp:41:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < v.size(); i++) {
                     ~~^~~~~~~~~~
mousetrap.cpp: In function 'int main()':
mousetrap.cpp:51:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d %d", &n, &t, &s);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:53:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &a, &b);
         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 20
• Subtask 2: 0 / 25
• Subtask 3: 0 / 20
• Subtask 4: 0 / 35