leetcode_033

public class  {
    public int search(int[] nums, int target) {
        return helper(nums, 0, nums.length - 1, target);
    }
    
    public int helper(int[] nums, int left, int right, int target) {
        if(left > right) {
            return -1;
        }
        
        int mid = left + (right-left) / 2;
        
        if(nums[mid] == target) {
            return mid;
        }
        
        int val1 = -1;
        int val2 = -1;
        
        
        // 无序的那一部分，继续用 helper
        if(nums[left] < nums[mid]) {
            val1 = binarySearch(nums,left, mid - 1,target);
            val2 = helper(nums,mid + 1, right,target);
        } else {
            val1 = binarySearch(nums,mid + 1, right,target);
            val2 = helper(nums,left, mid - 1,target);
        }
        
        if(val1 == -1) {
            return val2;
        } else {
            return val1;
        }
    }
    
    // 二叉查找
    public int binarySearch(int nums[], int left, int right, int target) {
        if(left > right) {
            return -1;
        }
        
        int mid = left + (right-left) / 2;
        
        if(nums[mid] == target) {
            return mid;
        }
        
        if(nums[mid] > target) {
            return binarySearch(nums, left, mid - 1, target);
        } else {
            return binarySearch(nums, mid + 1, right, target);
        }
    }
}