Two Sum
Code:
O(n):
class Solution { public: vector<int> twoSum(vector<int> &numbers, int target) { vector<int> res; map<int,int> mapping; int n=numbers.size(); for (int i=0; i<n; ++i) if (mapping[ target - numbers[i]]){ res.push_back(mapping[ target - numbers[i]]); res.push_back(i+1); } else mapping[ numbers[i] ] = i+1; return res; } };
O(nxm):
class Solution { public: vector<int> twoSum(vector<int> &numbers, int target) { vector<int> res; int n=numbers.size(); for(int i=0;i<n;i++) for(int j=i+1;j<n;j++) if(numbers[i]+numbers[j]==target){ res.push_back(i+1); res.push_back(j+1); return res; } return res; } };
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