Two Sum LeetCode Solution

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Here, We see Two Sum LeetCode problem Solution. This Leetcode problem done in many programming language like C++, Java, JavaScript, Python etc. with different approach.

List of all LeetCode Problem Solution
Two Sum LeetCode Solution

Two Sum LeetCode Solution

Problem Statement ->

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]

Java Solution -> (Using Brute Force)

class Solution {
    public int[] twoSum(int[] nums, int target) {
        for (int i = 0; i < nums.length; i++) {
            for (int j = i + 1; j < nums.length; j++) {
                if (nums[j] == target - nums[i]) {
                    return new int[] { i, j };
                }
            }
        }
        // In case there is no solution, we'll just return null
        return null;
    }
}

Code language: Java (java)

Python Solution -> (Using Brute Force)

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        for i in range(len(nums)):
            for j in range(i + 1, len(nums)):
                if nums[j] == target - nums[i]:
                    return [i, j]

Code language: Python (python)

Java Solution -> (Using Two-pass Hash Table)

class Solution {
    public int[] twoSum(int[] nums, int target) {
        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            map.put(nums[i], i);
        }
        for (int i = 0; i < nums.length; i++) {
            int complement = target - nums[i];
            if (map.containsKey(complement) && map.get(complement) != i) {
                return new int[] { i, map.get(complement) };
            }
        }
        // In case there is no solution, we'll just return null
        return null;
    }
}

Code language: Java (java)

Python Solution -> (Using Two-pass Hash Table)

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]] 

Code language: Python (python)

Java Solution -> (Using One-pass Hash Table)

class Solution {
    public int[] twoSum(int[] nums, int target) {
        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            int complement = target - nums[i];
            if (map.containsKey(complement)) {
                return new int[] { map.get(complement), i };
            }
            map.put(nums[i], i);
        }
        // In case there is no solution, we'll just return null
        return null;
    }
}

Code language: Java (java)

Python Solution -> (Using One-pass Hash Table)

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

Code language: Python (python)

Other Programming Language Solution :

C++ Solution ->

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        unordered_map<int, int> cache;
        vector<int> answer;
        
        for (size_t i = 0; i < nums.size(); ++i)
        {
            int needed_num = target - nums[i];
            
            if (cache.find(needed_num) != cache.end())
            {
                // We found it
                answer.push_back(cache[needed_num]);
                answer.push_back(i);
                return answer;
            }
            else
            {
                // Didn't find it
                cache.insert(make_pair(nums[i], i));
            }
        }
        return answer;
    }
};

Code language: C++ (cpp)

JavaScript Solution ->

var twoSum = function(nums, target) {
    let map = new Map;
    for (var i = 0; i < nums.length; i++) {
        let complement = target - nums[i];
        if (map.has(complement)) {
            return [map.get(complement), i]
        }
        map.set(nums[i], i);
    }
};

Code language: JavaScript (javascript)

Leetcode Two Sum, Two Sum python solution, Two Sum java solution, Two Sum JavaScript solution, Two Sum C++ solution

Two Sum python solution, Two Sum java solution, Two Sum JavaScript solution, Two Sum C++ solution

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