《程序员代码面试指南》第八章 数组和矩阵问题 数组的partition 调整

题目

数组的partition 调整

java代码

package com.lizhouwei.chapter8;

/**
 * @Description: 数组的partition 调整
 * @Author: lizhouwei
 * @CreateDate: 2018/5/9 21:24
 * @Modify by:
 * @ModifyDate:
 */
public class Chapter8_23 {
    public void leftUnique(int[] arr) {
        if (arr == null || arr.length < 2) {
            return;
        }
        int left = 0;
        int right = 1;
        while (right < arr.length) {
            if (arr[left] != arr[right++]) {
                swap(arr, ++left, right - 1);
            }
        }
    }

    public void sort(int[] arr) {
        int left = -1;
        int index = 0;
        int right = arr.length - 1;
        while (index < right) {
            if (arr[index] == 0) {
                swap(arr, index++, ++left);
            } else if (arr[index] == 2) {
                swap(arr, index, right--);
            } else {
                index++;
            }
        }
    }


    public void swap(int[] arr, int a, int b) {
        int temp = arr[a];
        arr[a] = arr[b];
        arr[b] = temp;
    }

    //测试
    public static void main(String[] args) {
        Chapter8_23 chapter = new Chapter8_23();
        int[] arr = {1, 2, 2, 2, 3, 3, 4, 5, 6, 6, 7, 7, 8, 8, 8, 9};
        chapter.leftUnique(arr);
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
        System.out.println();
        int[] arr1 = {1, 2, 0, 0, 1, 2, 2, 1, 0, 0};
        chapter.sort(arr1);
        for (int i = 0; i < arr1.length; i++) {
            System.out.print(arr1[i] + " ");
        }
    }

}

结果