《程序员代码面试指南》第八章 数组和矩阵问题 不重复打印排序数组中相加和为给定值的所有二元组和三元组

Posted 2020-11-03 lizhouwei

题目

不重复打印排序数组中相加和为给定值的所有二元组和三元组

java代码

package com.lizhouwei.chapter8;

/**
 * @Description: 不重复打印排序数组中相加和为给定值的所有二元组和三元组
 * @Author: lizhouwei
 * @CreateDate: 2018/5/7 21:27
 * @Modify by:
 * @ModifyDate:
 */
public class Chapter8_9 {

    public void printUniquePair(int[] arr, int k) {
        if (arr == null || arr.length < 2) {
            return;
        }
        int left = 0;
        int right = arr.length - 1;
        while (left < right) {
            if (arr[left] + arr[right] < k) {
                left++;
            } else if (arr[left] + arr[right] > k) {
                right--;
            } else {
                if (left == 0 || arr[left] != arr[left - 1]) {
                    System.out.println(arr[left] + "," + arr[right]);
                    left++;
                    right--;
                }
            }
        }
    }

    public void printUniqueTriad(int[] arr, int k) {
        for (int i = 0; i < arr.length - 2; i++) {
            if (i == 0 || arr[i] != arr[i - 1]) {
                printRest(arr, i, i + 1, arr.length - 1, k - arr[i]);
            }
        }
    }

    public void printRest(int[] arr, int pre, int left, int right, int k) {
        while (left < right) {
            if (arr[left] + arr[right] < k) {
                left++;
            } else if (arr[left] + arr[right] > k) {
                right--;
            } else {
                if (left == pre || arr[left] != arr[left - 1]) {
                    System.out.println(arr[pre] + "," + arr[left] + "," + arr[right]);
                    left++;
                    right--;
                }
            }
        }
    }

    //测试
    public static void main(String[] args) {
        Chapter8_9 chapter = new Chapter8_9();
        int[] arr = {-8, -4, -3, 0, 1, 2, 4, 5, 6, 9};
        System.out.println("数组 arr = {-8, -4, -3, 0, 1, 2, 4, 5, 6, 9}中和为10的二元组:");
        chapter.printUniquePair(arr, 10);
        System.out.println("数组 arr = {-8, -4, -3, 0, 1, 2, 4, 5, 6, 9}中和为10的三元组:");
        chapter.printUniqueTriad(arr, 10);
    }
}

结果