【codeforces 572A】Arrays

time limit per test2 seconds
memory limit per test256 megabytes
inputstandard input
outputstandard output
You are given two arrays A and B consisting of integers, sorted in non-decreasing order. Check whether it is possible to choose k numbers in array A and choose m numbers in array B so that any number chosen in the first array is strictly less than any number chosen in the second array.

Input
The first line contains two integers nA, nB (1 ≤ nA, nB ≤ 105), separated by a space — the sizes of arrays A and B, correspondingly.

The second line contains two integers k and m (1 ≤ k ≤ nA, 1 ≤ m ≤ nB), separated by a space.

The third line contains nA numbers a1, a2, … anA ( - 109 ≤ a1 ≤ a2 ≤ … ≤ anA ≤ 109), separated by spaces — elements of array A.

The fourth line contains nB integers b1, b2, … bnB ( - 109 ≤ b1 ≤ b2 ≤ … ≤ bnB ≤ 109), separated by spaces — elements of array B.

Output
Print “YES” (without the quotes), if you can choose k numbers in array A and m numbers in array B so that any number chosen in array A was strictly less than any number chosen in array B. Otherwise, print “NO” (without the quotes).

Examples
input
3 3
2 1
1 2 3
3 4 5
output
YES
input
3 3
3 3
1 2 3
3 4 5
output
NO
input
5 2
3 1
1 1 1 1 1
2 2
output
YES
Note
In the first sample test you can, for example, choose numbers 1 and 2 from array A and number 3 from array B (1 < 3 and 2 < 3).

In the second sample test the only way to choose k elements in the first array and m elements in the second one is to choose all numbers in both arrays, but then not all the numbers chosen in A will be less than all the numbers chosen in B: .

【题目链接】:http://codeforces.com/contest/572/problem/A

【题解】

比较a[k]和b[nb-m+1]就好;
如果小于就可以(选最小的k个和最大的m个);

【完整代码】

#include <bits/stdc++.h>
using namespace std;
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define LL long long
#define rep1(i,a,b) for (int i = a;i <= b;i++)
#define rep2(i,a,b) for (int i = a;i >= b;i--)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define rei(x) scanf("%d",&x)
#define rel(x) scanf("%I64d",&x)

typedef pair<int,int> pii;
typedef pair<LL,LL> pll;

const int MAXN = 1e5+100;
const int dx[9] = {0,1,-1,0,0,-1,-1,1,1};
const int dy[9] = {0,0,0,-1,1,-1,1,-1,1};
const double pi = acos(-1.0);

int na,nb,k,m;
int a[MAXN],b[MAXN];

int main()
{
    //freopen("F:\rush.txt","r",stdin);
    rei(na);rei(nb);
    rei(k);rei(m);
    rep1(i,1,na)
        rei(a[i]);
    rep1(i,1,nb)
        rei(b[i]);
    if (a[k] < b[nb-m+1])
        puts("YES");
    else
        puts("NO");

    return 0;
}