Solution 3sum

Author: doitduri

3sum/doitduri.swift

@@ -0,0 +1,43 @@
+import Foundation
+
+class Solution {
+    func threeSum(_ nums: [Int]) -> [[Int]] {
+        var result = [[Int]]()
+        let sortedNums = nums.sorted()
+        
+        for i in 0..<sortedNums.count - 2 {
+            if i > 0 && sortedNums[i] == sortedNums[i - 1] {
+                continue
+            }
+            
+            var leftNumber = i + 1
+            var rightNumber = sortedNums.count - 1
+            
+            while leftNumber < rightNumber {
+                let sum = sortedNums[i] + sortedNums[leftNumber] + sortedNums[rightNumber]
+                
+                if sum < 0 {
+                    leftNumber += 1
+                } else if sum > 0 {
+                    rightNumber -= 1
+                } else {
+                    result.append([sortedNums[i], sortedNums[leftNumber], sortedNums[rightNumber]])
+                    
+                    while leftNumber < rightNumber && sortedNums[leftNumber] == sortedNums[leftNumber + 1] {
+                        leftNumber += 1
+                    }
+                    
+                    while leftNumber < rightNumber && sortedNums[rightNumber] == sortedNums[rightNumber - 1] {
+                        rightNumber -= 1
+                    }
+                    
+                    leftNumber += 1
+                    rightNumber -= 1
+                }
+            }
+        }
+        
+        return result
+    }
+}
+