https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/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.
代码：
class Solution {
public:
vector<int> twoSum(vector<int>& numbers, int target) {
int l = 0, r = numbers.size() - 1;
for(int i = 0; i < numbers.size(); i ++) {
int sum = numbers[l] + numbers[r];
if(sum == target) return {l + 1, r + 1};
else if(sum < target) l ++;
else r --;
}
return {};
}
};