MergeSort

public class test {
	static int[] A = { 3, 10, 9, 8, 5, 6, 1, 2, 7, 4 };

	public static void Merge(int[] B, int i1, int j1, int i2, int j2) {
		int n = j2 - i1 + 1;
		int[] temp = new int[n];
		int k = 0, i = i1, j = i2;
		while (i <= j1 && j <= j2) {
			if (B[i] <= B[j]) {
				temp[k++] = B[i++];
			} else
				temp[k++] = B[j++];
		}
		while (i <= j1) {
			temp[k++] = B[i++];
		}
		while (j <= j2) {
			temp[k++] = B[j++];
		}
		for (k = 0; k < n; k++) {
			B[i1++] = temp[k];
		}
	}

	public static void MergeSort(int[] B) {
		int i1, i2, j1, j2;
		int size = 1;
		int n = B.length;
		while (size <= n) {
			i1 = 0;
			while (i1 < n) {
				j1 = i1 + size - 1;
				if(j1= n) {
					j2 = n - 1;
				} else {
					j2 = i2 + size - 1;
				}
				Merge(B, i1, j1, i2, j2);
				i1 = j2 + 1;
				}
				else break;
			}
			size*=2;
		}
	}

	public static void main(String[] args) {
		MergeSort(A);
		for (int i = 0; i < A.length; i++) {
			System.out.printf("%d\t", A[i]);
		}
	}
}

书上例子：又是扑克，一张张正面朝上 平铺，两堆两堆的合

分治的典型例子 用递归 治 分成的小问题