HDU 3530 Subsequence (单调队列)

Subsequence

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 3132    Accepted Submission(s): 1020

Problem Description

There is a sequence of integers. Your task is to find the longest subsequence that satisfies the following condition: the difference between the maximum element and the minimum element of the subsequence is no smaller than m and no larger than k.

 

Input

There are multiple test cases.
For each test case, the first line has three integers, n, m and k. n is the length of the sequence and is in the range [1, 100000]. m and k are in the range [0, 1000000]. The second line has n integers, which are all in the range [0, 1000000].
Proceed to the end of file.

 

Output

For each test case, print the length of the subsequence on a single line.

 

Sample Input

5 0 0 1 1 1 1 1 5 0 3 1 2 3 4 5

 

Sample Output

5 4

 

Source

2010 ACM-ICPC Multi-University Training Contest（10）——Host by HEU

 

Recommend

zhengfeng

 

#include<iostream>
#include<cstdio>
#include<cstring>

using namespace std;

const int maxn=100010;

int minQue[maxn],maxQue[maxn];
int minLeft,minRight;
int maxLeft,maxRight;
int num[maxn];

int main(){

    //freopen("input.txt","r",stdin);

    int n,m,k;
    while(~scanf("%d%d%d",&n,&m,&k)){
        minLeft=minRight=0;
        maxLeft=maxRight=0;
        int ans=0,now=1;
        for(int i=1;i<=n;i++){
            scanf("%d",&num[i]);
            while(minLeft<minRight && num[minQue[minRight-1]]>num[i])
                minRight--;
            minQue[minRight++]=i;
            while(maxLeft<maxRight && num[maxQue[maxRight-1]]<num[i])
                maxRight--;
            maxQue[maxRight++]=i;

            while(minLeft<minRight && maxLeft<maxRight && num[maxQue[maxLeft]]-num[minQue[minLeft]]>k){
                if(maxQue[maxLeft]<minQue[minLeft])
                    now=maxQue[maxLeft++]+1;
                else
                    now=minQue[minLeft++]+1;
            }
            if(minLeft<minRight && maxLeft<maxRight && num[maxQue[maxLeft]]-num[minQue[minLeft]]>=m){
                if(ans<i-now+1)
                    ans=i-now+1;
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}