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. Please note that 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.
Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2
解題思路
本題是two sum的變種題,其實(shí)比two sum還簡(jiǎn)單一些,因?yàn)橐呀?jīng)排好序了沐祷,直接采用頭尾下標(biāo)的方法喜爷。
vector<int> twoSum(vector<int>& numbers, int target) {
vector<int> res;
int number = numbers.size();
int l = 0, r = number -1;
while(l < r)
{
if(numbers[l] > target) break;
if(numbers[l] + numbers[r] == target)
{
res.push_back(l+1);
res.push_back(r+1);
return res;
}
else if(numbers[l] + numbers[r] < target)
l++;
else{
r--;
}
}
return res;
}