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package others;

import java.util.Arrays;

/**

* 合并排序,分成若干个子序列 对子序列排序 最后再把合并好的合并成一个整体

* @author

*

*/

public class MergeSort {

public static void main(String[] args) {

int[] input = {1,3,5,7,9,3,2,6};

sort(input,0,input.length-1);

System.out.println(Arrays.toString(input));

}

public static int[] sort(int[] input, int left, int right) {

int middle = (left + right) / 2;

if (left < right) {

// 中间的左边

sort(input,left,middle);

//中间的右边

sort(input,middle + 1,right);

// 左右合并

merge(input,left,middle,right);

}

return input;

}

public static void merge(int[] nums, int low, int mid, int high) {

int[] temp = new int[high - low + 1];

int i = low;// 左指针

int j = mid + 1;// 右指针

int k = 0;

// 把较小的数先移到新数组中

while (i <= mid && j <= high) {

if (nums[i] < nums[j]) {

temp[k++] = nums[i++];

} else {

temp[k++] = nums[j++];

}

}

// 把左边剩余的数移入数组

while (i <= mid) {

temp[k++] = nums[i++];

}

// 把右边边剩余的数移入数组

while (j <= high) {

temp[k++] = nums[j++];

}

// 把新数组中的数覆盖nums数组

for (int k2 = 0; k2 < temp.length; k2++) {

nums[k2 + low] = temp[k2];

}

}

}