Hdu 5806 NanoApe Loves Sequence Ⅱ(双指针)

Hdu 5806

题意：给出一个数组，求区间第k大的数大于等于m的区间个数

#include<queue>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define ll long long
#define inf 0x3f3f3f3f
using namespace std;
inline int read()
{int x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}return x*f;
}
const int N=2e5+10;
int a[N];
int main()
{int T=read();while(T--){int n=read(),m=read(),k=read();for(int i=0;i<n;i++) a[i]=read();int l=0,r=0,cnt=0;ll ans=0;while(l<=r&&r<n){while(r<n&&cnt<k){if(a[r++]>=m) cnt++;}if(r>n||cnt<k) break;if(cnt==k) ans+=n-r+1;while(cnt==k){if(a[l++]>=m) cnt--;if(cnt==k) ans+=n-r+1;}}printf("%lld\n",ans);}return 0;
}

Java版本实现，输入可能会导致超时，需要使用BufferedInputStream加速

import java.io.*;
import java.util.*;
class MyInputStream extends InputStream {  public BufferedInputStream bis = new BufferedInputStream(System.in);  public int read() throws IOException {  int i;  while ((i = bis.read()) < 48)  if (i == -1)  return -1;  int temp = 0;  while (i > 47) {  temp = temp * 10 + i - 48;  i = bis.read();  }  return temp;  }
}
public class Main
{static final int N=200005;static int a[]=new int[N];public static void main(String[] args) throws IOException{MyInputStream sc=new MyInputStream();int T=sc.read();Integer zero=new Integer("0");while(!zero.equals(T--)){int n=sc.read(),m=sc.read(),k=sc.read();for(int i=0;i<n;i++) a[i]=sc.read();int l=0,r=0,cnt=0;long ans=0;while(l<=r&&r<n){while(r<n&&cnt<k){if(a[r++]>=m) cnt++;}if(r>n||cnt<k) break;if(cnt==k) ans+=n-r+1;while(cnt==k){if(a[l++]>=m) cnt--;if(cnt==k) ans+=n-r+1;}}System.out.println(ans);}sc.close();}
}