题目

未排序数组中累加和为给定值的最长子数组系列问题

java代码

package com.lizhouwei.chapter8;import java.util.HashMap;import java.util.Map;/** * @Description: * @Author: lizhouwei * @CreateDate: 2018/5/7 21:57 * @Modify by: * @ModifyDate:*/public class Chapter8_11 {    public int getMaxLength(int[] arr, int k) {        if (arr == null) {            return 0;        }        Map
    
      map = new HashMap<>();        map.put(0, -1);        int sum = 0;        int maxLen = 0;        for (int i = 0; i < arr.length; i++) {            sum = sum + arr[i];            if (map.containsKey(sum - k)) {                maxLen = Math.max(maxLen, i - map.get(sum - k));            }            map.put(sum, i);        }        return maxLen;    }    //测试    public static void main(String[] args) {        Chapter8_11 chapter = new Chapter8_11();        int[] arr = {1, 2, 1, 1, 1};        System.out.print("数组 arr = {1, 2, 1, 1, 1}中和为3的最长子数组长度为:");        int maxLen= chapter.getMaxLength(arr, 3);        System.out.print(maxLen);    }}
    

结果