归并排序的思想及递归运行步骤详解

归并排序主体运行情况如下：

 归并排序算法java代码实现如下：

import java.util.Arrays;

import javax.sound.midi.MidiDevice;

public class MergeSort {
	public static void main(String[] args) {
		int[] a = { 1, 5, 6, 24,8,6,345,346 };
		mergeSort(a, 0, a.length - 1);
		System.out.println("归并排序结果=" + Arrays.toString(a));
	}

	private static void mergeSort(int[] a, int i, int j) {
		// TODO Auto-generated method stub
		int mid = (i + j) / 2;

		//System.out.print( mid +" ");
		if (i < j) {
			mergeSort(a, i, mid);
			mergeSort(a, mid + 1, j);
			merge(a, i, mid, j);
			
		}
	}

	private static void merge(int[] a, int low, int mid, int high) {
		// TODO Auto-generated method stub
		int i = low;
		int j = mid + 1;
		int k = 0;
		int[] tmp = new int[high - low + 1]; // 辅助数组
		while (i <= mid && j <= high) {
			if (a[i] < a[j]) {
				tmp[k++] = a[i++];
			} else {
				tmp[k++] = a[j++];
			}
		}
		while (i <= mid) {
			tmp[k++] = a[i++];
		}
		while (j <= high) {
			tmp[k++] = a[j++];
		}

		for (int x = 0; x < tmp.length; x++) {
			a[low++] = tmp[x];
		}

		for (int l = 0; l < tmp.length; l++) {
			System.out.print(tmp[l]+" ");
		}
		System.out.println();
	}
}

　　运行结果如下：