Problem 16: 3Sum Closest

16. 3Sum Closest/solution.c

@@ -0,0 +1,52 @@
+#include <math.h>
+
+
+void insertion_sort(int arr[], int n)
+{
+    for (int i = 1; i < n; ++i)
+    {
+        int key = arr[i];
+        int j   = i - 1;
+
+        while ((j >= 0) && (arr[j] > key))
+        {
+            arr[j + 1] = arr[j];
+            j          = j - 1;
+        }
+
+        arr[j + 1] = key;
+    }
+}
+
+/**
+ * Given a list of numbers, nums
+ * We need to find 3 integers at distinct indices in nums
+ * Such that their sum either equals or is the closest to 'target'
+ */
+int threeSumClosest(int* nums, int numsSize, int target)
+{
+    insertion_sort(nums, numsSize);
+    int closest = nums[0] + nums[1] + nums[2];
+
+    for (int i = 0; i < numsSize - 2; ++i)
+    {
+        int left  = i + 1;
+        int right = numsSize - 1;
+
+        while (left < right)
+        {
+            int curr_sum = nums[i] + nums[left] + nums[right];
+            if (abs(curr_sum - target) < abs(closest - target))
+                closest = curr_sum;
+
+            if (curr_sum < target)
+                left += 1;
+            else if (curr_sum > target)
+                right -= 1;
+            else
+                return curr_sum;
+        }
+    }
+
+    return closest;
+}

16. 3Sum Closest/solution.py

@@ -0,0 +1,30 @@
+from typing import List
+
+
+class Solution:
+    def threeSumClosest(self, nums: List[int], target: int) -> int:
+        """
+        Given a list of numbers, nums
+        We need to find 3 integers at distinct indices in nums
+        Such that their sum either equals or is the closest to 'target'
+        """
+        nums.sort()
+        closest = sum(nums[:3])
+
+        for i in range(len(nums) - 2):
+            left = i + 1
+            right = len(nums) - 1
+
+            while left < right:
+                current_sum = nums[i] + nums[left] + nums[right]
+                if abs(current_sum - target) < abs(closest - target):
+                    closest = current_sum
+
+                if current_sum < target:
+                    left += 1
+                elif current_sum > target:
+                    right -= 1
+                else:
+                    return current_sum
+
+        return closest