Submission #66660

#	Time	Username	Problem	Language	Result	Execution time	Memory
66660		HellAngel	Watching (JOI13_watching)	C++14	100 / 100	70 ms	9268 KiB

watching

#include <bits/stdc++.h>

using namespace std;

const int maxn = 2001;

int n, a[maxn], f[maxn][maxn], p, q, Next[maxn][2];

int bs(int x)
{
    int l = 1;
    int h = n;
    while(l <= h)
    {
        int mid = l + h >> 1;
        if(a[mid] < x) l = mid + 1;
        else h = mid - 1;
    }
    return l;
}

bool Check(int gau)
{
    for(int i = 1; i <= n; i++)
    {
        Next[i][0] = bs(a[i] + gau);
        Next[i][1] = bs(a[i] + 2 * gau);
    }
    f[0][0] = 1;
    for(int i = 0; i <= p; i++)
    {
        for(int j = 0; j <= q; j++)
        {
            if(i == 0 && j == 0) continue;
            int x = 0;
            if(i > 0)
            {
                x = max(x, Next[f[i - 1][j]][0]);
            }
            if(j > 0)
            {
                x = max(x, Next[f[i][j - 1]][1]);
            }
            if(x == n + 1) return true;
            f[i][j] = x;
        }
    }
    return false;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    //freopen("test.inp", "r", stdin);
    //freopen("test.out", "w", stdout);
    cin >> n >> p >> q;
    for(int i = 1; i <= n; i++)
    {
        cin >> a[i];
    }
    sort(a + 1, a + n + 1);
    if(p + q >= n) return cout << 1, 0;
    int l = 1;
    int h = 1e9;
    while(l <= h)
    {
        int mid = (l + h) / 2;
        if(Check(mid)) h = mid - 1;
        else l = mid + 1;
    }
    cout << l;
}

Compilation message (stderr)

watching.cpp: In function 'int bs(int)':
watching.cpp:15:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
         int mid = l + h >> 1;
                   ~~^~~

• Subtask 1: 50 / 50
• Subtask 2: 50 / 50