Skip to content

167. Two Sum II - Input array is sorted

难度: Easy

刷题内容

原题连接

  • https://leetcode.com/problems/two-sum-ii-input-array-is-sorted

内容描述

Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2.

Note:

Your returned answers (both index1 and index2) are not zero-based.
You may assume that each input would have exactly one solution and you may not use the same element twice.
Example:

Input: numbers = [2,7,11,15], target = 9
Output: [1,2]
Explanation: The sum of 2 and 7 is 9. Therefore index1 = 1, index2 = 2.

解题方案

思路 1 **- 时间复杂度: O(log2 N)*- 空间复杂度: O(n)***

  • 使用贪心算法,用左右的数字开始加,如果数字大于目标right--,反之left++

代码:

/**
 * @param {number[]} numbers
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(numbers, target) {
    if(numbers.length===0)
        return [];
    var left = 0,right = numbers.length-1;
    while(right>left){
        if(numbers[right]+numbers[left]>target)
            right--;
        else if(numbers[right]+numbers[left]<target)
            left++;
        else return [left+1,right+1];
    }
    return [];
};


回到顶部