Given an array of integers, 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.
Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2
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O(N) time / O(N) space
class Solution {
public:
vector
twoSum(vector
&numbers, int target) { vector
result; if (numbers.size() < 2) return result; map
mp; int i, j; for (i = 0; i < numbers.size(); i++){ map
::iterator it_1 = mp.find(numbers[i]); if (it_1 == mp.end()) { mp.insert(make_pair(numbers[i], i + 1)); } map
::iterator it_2 = mp.find(target - numbers[i]); if (it_2 != mp.end()) { j = mp[target - numbers[i]]; if(j
j i+1:j); } };