167. Two Sum II - Input array is sorted
167. Two Sum II - Input array is sorted
难度：Easy
内容
原题链接：https://leetcode.com/problems/two-sum-ii-input-array-is-sorted
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.
思路
关键点：
- 升序排列
- 一定有解
代码
class Solution {
public:
vector<int> twoSum(vector<int>& numbers, int target) {
int left = 0, right = numbers.size() - 1;
while (left < right) {
int sum = numbers[left] + numbers[right];
if (sum < target)
left++;
else if (sum > target)
right--;
else
return {left + 1, right + 1};
}
return {0, 0};
}
};
