# Two Sum

ID: 1; Easy

## Solution 1 (Go)

``````func twoSum(nums []int, target int) []int {
var indices []int
for i := 0; i < len(nums)-1; i++ {
for j := i+1; j < len(nums) ; j++ {
if nums[i] + nums[j] == target {
indices = append(indices, i, j)
}
}
}
return indices
}``````

## Solution 2 (Go)

``````func twoSum(nums []int, target int) []int {
m := make(map[int]int)
for i,v := range nums {
j := target - v
if _, ok := m[j]; ok {
return []int{m[j], i}
}
m[v] = i
}
return nil
}``````

## Solution 3 (Java)

``````public class Solution {
/**
* @param numbers: An array of Integer
* @param target: target = numbers[index1] + numbers[index2]
* @return: [index1, index2] (index1 < index2)
*/
public int[] twoSum(int[] numbers, int target) {
// <number, its index>
Map<Integer, Integer> map = new HashMap<>();
for (int i = 0; i < numbers.length; i++) {
int j = target - numbers[i];
if (map.containsKey(j)) {
return new int[]{map.get(j), i};
}
map.put(numbers[i], i);
}
return null;
}
}``````

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