【LeetCode-剑指offer】-- 6.两数之和II-输入有序数组

6.两数之和II-输入有序数组

方法一：双指针

class Solution {
    public int[] twoSum(int[] numbers, int target) {
        int left = 0,right = numbers.length - 1;
        while(left <= right){
            int sum = numbers[left] + numbers[right];
            if(sum == target){
                return new int[]{left,right};
            }
            else if(sum < target){
                left++;
            }else{
                right--;
            }
        }
        return new int[]{-1,-1};
    }
}

方法二：二分查找

class Solution {
    public int[] twoSum(int[] numbers, int target) {
        for(int i = 0 ;i < numbers.length;i++){
            int left = i + 1,right = numbers.length - 1;
            while(left <= right){
                int mid = left + (right - left) / 2;
                if(numbers[mid] == target - numbers[i]){
                    return new int[]{i,mid};
                }else if(numbers[mid] > target - numbers[i]){
                    right =  mid - 1;
                }else{
                    left = mid + 1;
                }
            }
        }
        return new int[]{-1,-1};
    }
}