add Two Sum task

Two Sum/Solution.java

@@ -0,0 +1,35 @@
+import java.util.Arrays;
+import java.util.HashMap;
+
+class Solution {
+    public static void main(String[] args) {
+      int[] test1 = {2, 7, 11, 15}; int target1 = 9;
+      int[] test2 = {3, 2, 4}; int target2 = 6;
+      int[] test3 = {3, 3}; int target3 = 6;
+
+
+      System.out.println("twoSum( " + Arrays.toString(test1) + ", " + target1 + " ): " + Arrays.toString(twoSum(test1, target1)));
+      System.out.println("twoSum( " + Arrays.toString(test2) + ", " + target2 + " ): " + Arrays.toString(twoSum(test2, target2)));
+      System.out.println("twoSum( " + Arrays.toString(test3) + ", " + target3 + " ): " + Arrays.toString(twoSum(test3, target3)));
+
+    }
+
+    static int[] twoSum(int[] nums, int target) {
+        int[] res = new int[2];
+
+        HashMap<Integer, Integer> d = new HashMap<>();
+
+        for (int i = 0; i < nums.length; i++) {
+          var remainderIdx = d.get(target - nums[i]);
+          if (remainderIdx != null) {
+            res[0] = i;
+            res[1] = remainderIdx;
+            return res;
+          } else {
+            d.put(nums[i], i);
+          }
+        }
+        
+        return res;
+    }
+}

Two Sum/solution.c

@@ -0,0 +1,48 @@
+#include <stdlib.h>
+
+typedef struct {
+    int key;
+    int value;
+    int used;
+} Entry;
+
+int hash(int key, int size) {
+    return (key % size + size) % size;
+}
+
+int* twoSum(int* nums, int numsSize, int target, int* returnSize) {
+
+    int tableSize = numsSize * 2;
+    Entry* table = calloc(tableSize, sizeof(Entry));
+
+    int* res = malloc(sizeof(int) * 2);
+    *returnSize = 2;
+
+    for (int i = 0; i < numsSize; i++) {
+        int complement = target - nums[i];
+        int h = hash(complement, tableSize);
+
+        while (table[h].used) {
+            if (table[h].key == complement) {
+                res[0] = i;
+                res[1] = table[h].value;
+                free(table);
+                return res;
+            }
+            h = (h + 1) % tableSize;
+        }
+
+        h = hash(nums[i], tableSize);
+        while (table[h].used) {
+            h = (h + 1) % tableSize;
+        }
+
+        table[h].used = 1;
+        table[h].key = nums[i];
+        table[h].value = i;
+    }
+
+    free(table);
+    return res;
+}
+

Two Sum/solution.cpp

@@ -0,0 +1,44 @@
+#include <iostream>
+#include <unordered_map>
+#include <vector>
+
+using namespace std;
+
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+      vector<int> res(2);
+
+      unordered_map<int, int> d;
+
+      for (size_t i = 0; i < nums.size(); i++) {
+        if (d.find(target - nums[i]) != d.end()) {
+          res[0] = i;
+          res[1] = d[target - nums[i]];
+          return res;
+        } else {
+          d[nums[i]] = i;
+        }
+      }
+
+      return res;
+    }
+};
+
+int main (int argc, char *argv[]) {
+  Solution s;
+  
+  vector<int> test1 = {2, 7, 11, 15}; int target1 = 9;
+  vector<int> test2 = {3, 2, 4}; int target2 = 6;
+  vector<int> test3 = {3, 3}; int target3 = 6;
+  
+  vector<int> res1 = s.twoSum(test1, target1);
+  cout << res1[0] << ' ' << res1[1] << endl;
+  vector<int> res2 = s.twoSum(test2, target2);
+  cout << res2[0] << ' ' << res2[1] << endl;
+  vector<int> res3 = s.twoSum(test3, target3);
+  cout << res3[0] << ' ' << res3[1] << endl;
+
+  return 0;
+}
+

Two Sum/solution.py

@@ -0,0 +1,10 @@
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        d: dict = {}
+
+        for i in range(len(nums)):
+            if (target - nums[i]) in d.keys():
+                return [i, d[target - nums[i]]]
+            else:
+                d[nums[i]] = i
+