LeetCode - 1. TwoSum

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);        }        return null;    }}

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

public class Solution {    public int[] TwoSum(int[] nums, int target) {        Dictionary<int, int> map = new Dictionary<int, int>();        for(int i = 0; i < nums.Length; i++){            int num = nums[i];            int complement = target - num;            if (map.ContainsKey(complement)){                return new int[] {map[complement], i};            }else if(!map.ContainsKey(num)){                map.Add(num, i);            }        }        return null;    }}

func twoSum(nums []int, target int) []int {    mapNum := make(map[int]int)    for i, num := range nums{        var complement int = target - num        // check val is in map        if val, ok := mapNum[complement]; ok {            return []int{i, val}        }        mapNum[num] = i    }    return nil}

class Solution {public:    vector<int> twoSum(vector<int>& nums, int target) {        map<int, int> mapNum;        for(int i = 0; i < nums.size(); i++){            int num = nums[i];            int complement = target - num;            if (mapNum.count(complement) > 0){                return {mapNum[complement], i};            } else {                mapNum.insert({num, i});            }        }        return {-1, -1};    }};

struct number_hash {  int value;  int index;  UT_hash_handle hh;};void destroy_table(struct number_hash** table) {  struct number_hash* curr;  struct number_hash* tmp;  HASH_ITER(hh, *table, curr, tmp) {    HASH_DEL(*table, curr);    free(curr);  }}int* twoSum(int* nums, int numsSize, int target, int* returnSize) {  struct number_hash* table = NULL;  struct number_hash* element;  int* ret = (int*) malloc(2 * sizeof(int));  int remaining;  for (int i = 0; i < numsSize; ++i) {    remaining = target - nums[i];    // Find if there has already been an element such that the sum is target    HASH_FIND_INT(table, &remaining, element);    if (element) {      ret[0] = element->index;      ret[1] = i;      break;    }    // Add the new number to the hash table if it doesn't exist already    HASH_FIND_INT(table, &nums[i], element);    if (!element) {      element = (struct number_hash *) malloc(sizeof(*element));      element->value = nums[i];      element->index = i;      HASH_ADD_INT(table, value, element);    }  }  destroy_table(&table);  *returnSize = 2;  return ret;}