Blue Bridge Cup algorithm training interval k large number query (Java solution)

Problem Description

Given a sequence, each time it asks which number is the largest number from the lth number to the kth number in the sequence.

Input format

The first line contains a number n, which represents the length of the sequence.

The second line contains n positive integers, representing a given sequence.

The third contains a positive integer m, which represents the number of queries.

In the next m lines, there are three numbers l, r, and K in each line, indicating which of the l-th to r-th numbers of the query sequence from left to right, which is the largest number K from the largest to the smallest. Sequence elements are numbered starting from 1.

Output format

A total of m lines are output, with a number in each line, indicating the answer to the query.

Sample input

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

Sample output

4
2

Data scale and convention

For 30% of the data, n,m<=100;

For 100% data, n,m<=1000;

Ensure that k<=(r-l+1) and the number in the sequence<=106.

Linear selection algorithm implementation

import java.util.Scanner;

public class Main {
    
    
    private static Scanner scanner = new Scanner(System.in);
    private static int n,m;
    private static int[] nums;
    private static int l,r,k;

    public static void main(String[] args) {
    
    
        n = scanner.nextInt();
        nums = new int[n];
        for (int i = 0; i < n; i++) {
    
    
            nums[i] = scanner.nextInt();
        }
        m = scanner.nextInt();
        for (int i = 0; i < m; i++) {
    
    
            l = scanner.nextInt();
            r = scanner.nextInt();
            k = scanner.nextInt();
            int[] numsTemp = new int[r - l + 1];
            for (int j = 0; j < r-l+1; j++) {
    
    
                numsTemp[j] = nums[l-1+j];
            }
            System.out.println(lineSearch(numsTemp,0,r-l,k));
        }
    }

    /**
     * 线性从大到小第几个
     * @param arr
     */
    private static int lineSearch(int[] arr,int left,int right,int k){
    
    
        if (left >= right) return arr[left];
        int point = arr[left];
        int i = left;
        int j = right;
        while (i < j) {
    
    
            while (i < j && arr[j] <= point) j--;
            arr[i] = arr[j];
            while (i < j && arr[i] >= point) i++;
            arr[j] = arr[i];
        }
        if(j - left + 1 == k) return point;
        arr[j] = point;
        if (j - left + 1 < k) return lineSearch(arr,j+1,right,k-j-1+left);
        return lineSearch(arr,left,j-1,k);
    }
}