Two Sum

 Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

 

Example 1:

Input: nums = [2,7,11,15], target = 9
Output: [0,1]
Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].

Example 2:

Input: nums = [3,2,4], target = 6
Output: [1,2]

Example 3:

Input: nums = [3,3], target = 6
Output: [0,1]

nums=[3,2,4]

MyPYTHON

// accepted

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        #if  not(2<=len(nums)<=1e4) or not(-1e9<=target<=1e9):
            #print("error1")
            #return


        
        result=[]
        a=False
        for i in range(len(nums)):
            for j in range(i+1,len(nums)):
                
                if nums[i]+nums[j]==target:
                    result.append(i)
                    result.append(j)
                    a=True
                    break
            if a:
                break
        return result
nums=[3,2,4]
target=6
a=Solution()
print(a.twoSum(nums,target))




My_OOP code 

//time limit exceeded

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        if  not(2<=len(nums)<=1e4) or not(-1e9<=target<=1e9):
            print("error1")
            return


        
        result=[]
        a=False
        for i in nums:
            for j in range(len(nums)):
                if not(-1e9<=nums[j]<=1e9):
                    print("error2")
                    return 
                if nums.index(i) == j:
                    continue
                elif i+nums[j]==target:
                    result.append(nums.index(i))
                    result.append(j)
                    a=True
                    break
            if a:
                break
        return result
nums=[3,2,4]
target=9
a=Solution()
a.twoSum(nums,target)

Leet_OOP code
(1)

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        hashmap = {}
        for i in range(len(nums)):
            hashmap[nums[i]] = i
        for i in range(len(nums)):
            complement = target - nums[i]
            if complement in hashmap and hashmap[complement] != i:
                return [i, hashmap[complement]] 
(2)
class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        hashmap = {}
        for i in range(len(nums)):
            complement = target - nums[i]
            if complement in hashmap:
                return [i, hashmap[complement]]
            hashmap[nums[i]] = i

My C++ CODE
class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        vector<int>result;                  // or vector<int>result(2);
        int size= nums.size();
        for (int i = 0;i<size - 1;i++)
        {
           for (int j = i+1;j<size;j++)
           {
               if (nums[i]+nums[j]==target)
               {
                   result.push_back(i); // or result[0]=i;
          result.push_back(j); // or   result[1]=j;
                   return result;                   

                  

               }
               
           }
        }
        return result;
    }
};