Two Sum Problem Java Solution - The Coding Shala

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Two Sum Problem Java Solution

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

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

Example:
Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

Two Sum Problem Java Program

Method 1:
We can use HashMap to store value and index.

Java Code: 

class Solution {
    public int[] twoSum(int[] nums, int target) {
        int[] ans = new int[2];
        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
        for(int i=0; i<nums.length; i++){
            int val = nums[i];
            if(map.containsKey(target-val)){
                ans[0] = map.get(target-val);
                ans[1] = i;
                return ans;
            }
            map.put(val, i);
        }
        return ans;
    }
}




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