Added 3Sum Closest

Author: gahogg

3Sum Closest - Leetcode 16/3Sum Closest - Leetcode 16.cpp

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+#include <vector>
+#include <algorithm>
+#include <cstdlib>
+
+class Solution {
+public:
+    int threeSumClosest(std::vector<int>& nums, int target) {
+        int n = nums.size();
+        std::sort(nums.begin(), nums.end());
+        int closestSum = INT_MAX;
+
+        for (int i = 0; i < n; i++) {
+            if (i > 0 && nums[i] == nums[i - 1]) continue;
+
+            int lo = i + 1, hi = n - 1;
+            while (lo < hi) {
+                int curSum = nums[i] + nums[lo] + nums[hi];
+
+                if (std::abs(curSum - target) < std::abs(closestSum - target)) {
+                    closestSum = curSum;
+                }
+
+                if (curSum == target) {
+                    return curSum;
+                } else if (curSum < target) {
+                    lo++;
+                } else {
+                    hi--;
+                }
+            }
+        }
+        return closestSum;
+    }
+};

3Sum Closest - Leetcode 16/3Sum Closest - Leetcode 16.java

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+import java.util.Arrays;
+
+public class Solution {
+    public int threeSumClosest(int[] nums, int target) {
+        int n = nums.length;
+        Arrays.sort(nums);
+        int closestSum = Integer.MAX_VALUE;
+
+        for (int i = 0; i < n; i++) {
+            if (i > 0 && nums[i] == nums[i - 1]) continue;
+
+            int lo = i + 1, hi = n - 1;
+            while (lo < hi) {
+                int curSum = nums[i] + nums[lo] + nums[hi];
+
+                if (Math.abs(curSum - target) < Math.abs(closestSum - target)) {
+                    closestSum = curSum;
+                }
+
+                if (curSum == target) {
+                    return curSum;
+                } else if (curSum < target) {
+                    lo++;
+                } else {
+                    hi--;
+                }
+            }
+        }
+        return closestSum;
+    }
+}

3Sum Closest - Leetcode 16/3Sum Closest - Leetcode 16.js

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+var threeSumClosest = function(nums, target) {
+    nums.sort((a, b) => a - b);
+    let n = nums.length;
+    let closestSum = Infinity;
+
+    for (let i = 0; i < n; i++) {
+        if (i > 0 && nums[i] === nums[i - 1]) continue;
+
+        let lo = i + 1, hi = n - 1;
+        while (lo < hi) {
+            let curSum = nums[i] + nums[lo] + nums[hi];
+
+            if (Math.abs(curSum - target) < Math.abs(closestSum - target)) {
+                closestSum = curSum;
+            }
+
+            if (curSum === target) {
+                return curSum;
+            } else if (curSum < target) {
+                lo++;
+            } else {
+                hi--;
+            }
+        }
+    }
+    return closestSum;
+};

3Sum Closest - Leetcode 16/3Sum Closest - Leetcode 16.py

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+class Solution:
+    def threeSumClosest(self, nums: List[int], target: int) -> int:
+        n = len(nums)
+        nums.sort()
+        closest_sum = float('inf')
+
+        for i in range(n):
+            if i > 0 and nums[i] == nums[i-1]:
+                continue
+
+            lo, hi = i + 1, n - 1
+            while lo < hi:
+                cur_sum = nums[i] + nums[lo] + nums[hi]
+
+                if abs(cur_sum - target) < abs(closest_sum - target):
+                    closest_sum = cur_sum
+
+                if cur_sum == target:
+                    return cur_sum
+                elif cur_sum < target:
+                    lo += 1
+                else:
+                    hi -= 1
+
+        return closest_sum
+        # Time: O(n^2)
+        # Space: O(n)