Submission #131549

#	Time	Username	Problem	Language	Result	Execution time	Memory
131549		SamAnd	Mousetrap (CEOI17_mousetrap)	C++17	20 / 100	2 ms	376 KiB

mousetrap

#include <bits/stdc++.h>
using namespace std;
const int N = 12, INF = 1000000009;

int n, t, m;
vector<int> a[N];

bool c[N];
void dfs0(int x, int p)
{
    if (x == t)
    {
        c[x] = true;
        return;
    }
    for (int i = 0; i < a[x].size(); ++i)
    {
        int h = a[x][i];
        if (h == p)
            continue;
        dfs0(h, x);
        if (c[h])
        {
            c[x] = true;
            return;
        }
    }
}

void rec(int x, int p, int i, int q, int sq, vector<int> qq);

int dp[N][N];
bool cc[N][N];
void dfs(int x, int q, int p)
{
    if (cc[x][q])
        return;
    cc[x][q] = true;
    if (x == t)
    {
        dp[x][q] = 0;
        return;
    }
    vector<int> v;
    rec(x, p, 0, q, q, v);
}

void rec(int x, int p, int i, int q, int sq, vector<int> qq)
{
    if (i == a[x].size())
    {
        vector<int> v;
        int vv = 0;
        for (int ii = 0; ii < a[x].size(); ++ii)
        {
            int h = a[x][ii];
            if (h == p)
                continue;
            if (!c[h])
            {
                dfs(h, qq[ii], x);
                v.push_back(dp[h][qq[ii]]);
            }
            else
            {
                dfs(h, qq[ii] + 1, x);
                vv = dp[h][qq[ii] + 1];
            }
        }
        sort(v.begin(), v.end());
        int yans = 0;
        for (int i = v.size() - q - 2; i >= 0; i -= 2)
            yans += v[i];
        yans += v.size();
        yans += vv;
        dp[x][sq] = min(dp[x][sq], yans);
        return;
    }
    if (a[x][i] == p)
    {
        qq.push_back(0);
        rec(x, p, i + 1, q, sq, qq);
        qq.pop_back();
        return;
    }
    for (int j = 0; j <= q; ++j)
    {
        qq.push_back(j);
        rec(x, p, i + 1, q - j, sq, qq);
        qq.pop_back();
    }
}

int main()
{
    //freopen("input.txt", "r", stdin);
    scanf("%d%d%d", &n, &t, &m);
    for (int i = 0; i < n - 1; ++i)
    {
        int x, y;
        scanf("%d%d", &x, &y);
        a[x].push_back(y);
        a[y].push_back(x);
    }
    dfs0(m, m);
    for (int x = 1; x <= n; ++x)
    {
        for (int i = 0; i < N; ++i)
        {
            dp[x][i] = INF;
        }
    }
    dfs(m, 0, m);
    cout << dp[m][0] << endl;
    return 0;
}

Compilation message (stderr)

mousetrap.cpp: In function 'void dfs0(int, int)':
mousetrap.cpp:16:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < a[x].size(); ++i)
                     ~~^~~~~~~~~~~~~
mousetrap.cpp: In function 'void rec(int, int, int, int, int, std::vector<int>)':
mousetrap.cpp:50:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (i == a[x].size())
         ~~^~~~~~~~~~~~~~
mousetrap.cpp:54:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int ii = 0; ii < a[x].size(); ++ii)
                          ~~~^~~~~~~~~~~~~
mousetrap.cpp: In function 'int main()':
mousetrap.cpp:97:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d", &n, &t, &m);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:101:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &x, &y);
         ~~~~~^~~~~~~~~~~~~~~~

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