[leetcode]35. Search Insert Position(Java)

leetcode：https://leetcode.com/problems/search-insert-position/#/description

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You may assume no duplicates in the array.

Here are few examples.
[1,3,5,6], 5 → 2
[1,3,5,6], 2 → 1
[1,3,5,6], 7 → 4
[1,3,5,6], 0 → 0

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Java Code:

package go.jacob.day621;

/**
 * [leetcode]35. Search Insert Position
 * 
 * @author Administrator
 *
 */
public class Demo2 {
	/*
	 * 二分查找的应用：循环解法
	 */
	public int searchInsert(int[] nums, int target) {
		if (nums == null || nums.length < 1)
			return 0;
		int left = 0, right = nums.length - 1;
		while (left <= right) {
			int mid = left + (right - left) / 2;
			if (nums[mid] == target)
				return mid;
			else if (target < nums[mid])
				right = mid - 1;
			else
				left = mid + 1;
		}
		return left;
	}

	/*
	 * 二分查找的应用：递归解法
	 */
	public int searchInsert_1(int[] nums, int target) {
		if (nums == null || nums.length < 1)
			return 0;
		int index = binarySearch(nums, target, 0, nums.length - 1);
		return index;
	}

	/*
	 * 二分查找
	 */
	private int binarySearch(int[] nums, int target, int left, int right) {
		if (right < left)
			return left;
		int mid = left + (right - left) / 2;
		if (target == nums[mid])
			return mid;
		if (target > nums[mid])
			return binarySearch(nums, target, mid + 1, right);
		else
			return binarySearch(nums, target, left, mid - 1);
	}
}