查找-二分查找(折半查找)

前提要求：

1. 采用顺序表存储
2. 元素有序排序列

	// 非递归二分查找
	public int binarySearch(int[] a, int target) {
		int l = 0, h = a.length - 1;
		while (l <= h) {
			int mid = (l + h) / 2;
			if (a[mid] == target) return mid;
			else if (a[mid] < target) l = mid + 1;
			else h = mid - 1;
		}
		return -1;
	}

	// 递归二分
	public int binarySearch(int[] a, int l, int h, int t) {
		// 递归出口
		if (t < a[l] || t > a[h] || l > h) return -1;
		int mid = (l + h) / 2;
		if (a[mid] == t) return mid;
		else if (a[mid] < t) {
			l = mid + 1;
			return binarySearch(a, l, h, t);
		} else {
			h = mid - 1;
			return binarySearch(a, l, h, t);
		}
	}

参考链接