3sum solution

Author: jinvicky

3sum/jinvicky.java

@@ -0,0 +1,38 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+// https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/description/ 문제를 풀고 다시 풀었습니다.
+class Solution {
+    public List<List<Integer>> threeSum(int[] nums) {
+        List<List<Integer>> res = new ArrayList<>();
+        Arrays.sort(nums);
+
+        for (int i = 0; i < nums.length; i++) {
+            if (i > 0 && nums[i] == nums[i-1]) {
+                continue;
+            }
+
+            int j = i + 1;
+            int k = nums.length - 1;
+
+            while (j < k) {
+                int total = nums[i] + nums[j] + nums[k];
+
+                if (total > 0) {
+                    k--;
+                } else if (total < 0) {
+                    j++;
+                } else {
+                    res.add(Arrays.asList(nums[i], nums[j], nums[k]));
+                    j++;
+
+                    while (nums[j] == nums[j-1] && j < k) {
+                        j++;
+                    }
+                }
+            }
+        }
+        return res;
+    }
+}