Submission #43046

#	Time	Username	Problem	Language	Result	Execution time	Memory
43046		RayaBurong25_1	Mousetrap (CEOI17_mousetrap)	C++14	45 / 100	1490 ms	64692 KiB

mousetrap

#include <stdio.h>
#include <vector>
std::vector<int> AdjList[1000005];
int PhaseII[1000005];
int m, t, T;
int MT[1000005];
int between;
void findMT(int u, int pa)
{
    if (u == t)
    {
        MT[u] = t;
        return;
    }
    int i, v, s = AdjList[u].size();
    for (i = 0; i < s; i++)
    {
        v = AdjList[u][i];
        if (v != pa)
        {
            findMT(v, u);
            if (MT[v])
                MT[u] = v;
        }
    }
}
void calcPhaseII(int u, int pa)
{
    int i, v, s = AdjList[u].size();
    int S = s;
    for (i = 0; i < s; i++)
    {
        v = AdjList[u][i];
        if (v != pa && MT[v])
            S--;
    }
    if (S == 1 || S == 2)
        PhaseII[u] = 1 - (pa == T);
    else if (pa == T)
        PhaseII[u] = S - 3;
    else
        PhaseII[u] = S - 2;
    PhaseII[u] += PhaseII[pa];
    // printf("u%d PhaseII%d\n", u, PhaseII[u]);
    for (i = 0; i < s; i++)
    {
        v = AdjList[u][i];
        if (v != pa && !MT[v])
            calcPhaseII(v, u);
    }
}
int PhaseI[1000005];
int min(int a, int b)
{
    return (a < b)?a:b;
}
void calcPhaseI(int u, int pa)
{
    int i, v, s = AdjList[u].size();
    int S = s;
    for (i = 0; i < s; i++)
    {
        v = AdjList[u][i];
        if (v != pa && MT[v])
            S--;
    }
    int p = PhaseII[u], q = PhaseII[u];
    for (i = 0; i < s; i++)
    {
        v = AdjList[u][i];
        if (v != pa && !MT[v])
        {
            calcPhaseI(v, u);
            if (PhaseI[v] >= p)
            {
                q = p;
                p = PhaseI[v];
            }
            else if (PhaseI[v] >= q)
                q = PhaseI[v];
        }
    }
    if (S == 1)
        PhaseI[u] = q;
    else
        PhaseI[u] = 1 + q;
    // printf("u%d PhaseI%d\n", u, PhaseI[u]);
}
int main()
{
    int n;
    scanf("%d %d %d", &n, &t, &m);
    int i, u, v;
    for (i = 0; i < n - 1; i++)
    {
        scanf("%d %d", &u, &v);
        AdjList[u].push_back(v);
        AdjList[v].push_back(u);
    }
    findMT(m, 0);
    for (i = 1; i <= n; i++)
    {
        // printf("MT %d\n", MT[i]);
        if (MT[i] && i != m && i != t)
            between += AdjList[i].size() - 2;
    }
    int ans = 0;
    u = m;
    while (u != t)
    {
        T = MT[u];
        calcPhaseII(u, T);
        calcPhaseI(u, T);
        ans += PhaseI[u];
        u = MT[u];
        break;
        // printf("ans %d\n", ans);
    }
    // printf("ans %d between %d\n", ans, between);
    ans += between;
    printf("%d", ans);
}

Compilation message (stderr)

mousetrap.cpp: In function 'int main()':
mousetrap.cpp:92:34: 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:96:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &u, &v);
                               ^

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