MergeSort

 MergeSort is a sample solution from the idea Dive - and - Conquer.

I show my code below:

 

java 代码

public class MergeSort {

    public static void sort(int[] array, int i, int j) {
        if (j-i == 1) {
            if (array[i]>array[j]) {
                int tmp = array[i];
                array[i] = array[j];
                array[j] = tmp;
            }
        } else {
            int mid = (i + j - 1) / 2;
            sort(array, i, mid);
            sort(array, mid+1, j);
            int[] newArray = merge(array, i, mid, mid+1, j);
            int k = 0;
            for (int index = i; index<=j; index++) {
                array[index] = newArray[k];
                k++;
            }
        }
    }

    public static int[] merge(int[] array, int i, int m, int j, int n) {
        int[] newArray = new int[n-i+1];
        int k = 0;
        while ((i<=m) && (j<=n)) {
            if (array[i]<array[j]) {
                newArray[k] = array[i];
                i++;
                k++;
            } else {
                newArray[k] = array[j];
                j++;
                k++;
            }
        }
        if (i>m) {
            for ( ; j<=n; j++) {
                newArray[k++] = array[j];
            }
        } else {
            for ( ; i<=m; i++) {
                newArray[k++] = array[i];
            }
        }
        return newArray;
    }

    public static void main(String[] args) {
        int[] array = {1, 4, 2, 5, 2, 6, 3, 0};
        sort(array, 0, array.length - 1);
        for (int i=0; i<array.length; i++) {
            System.out.print(array[i] + " ");
        }
    }
}