Description
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.
一.题目理解
这道题和第1题极像,区别在于给定的数组已经排好序,输出要求下标加1且顺序递增。
二.题目解答
这里直接给出代码
class Solution { public: vector<int> twoSum(vector<int>& numbers, int target) { vector<int> ans; unordered_map<int,int> umap; for(int i = 0; i < numbers.size(); i++) { if(umap.count(target - numbers[i])) { ans.push_back(umap[target - numbers[i]] + 1); ans.push_back(i+1); return ans; } umap[numbers[i]] = i; } return ans; } };