【c/c++】 leetcode 167. Two Sum II - Input array is sorted (easy)
阿新 • • 發佈:2018-12-12
167. Two Sum II - Input array is sorted (easy)
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
一個start和一個end位置指向首尾,如果(numbers[start] + numbers[end] )> target,說明要減小左邊的值,所以減小end的位置;
如果(numbers[start] + numbers[end] )< target,說明要增大左邊的值,所以增大start的位置;
這道題簡單在只有一對滿足所求條件 且 vector是增序
class Solution { public: vector<int> twoSum(vector<int>& numbers, int target) { vector<int> twoNum; int len = numbers.size(); int start = 0; int end = len - 1; while(start <= end){ if((numbers[start] + numbers[end]) > target) end--; else if((numbers[start] + numbers[end]) < target) start++; else if((numbers[start] + numbers[end]) == target){ twoNum.push_back(start + 1); twoNum.push_back(end + 1); return twoNum; } } } };
4ms beats 99.28%