3sum

Author: taekwon-dev

3sum/taekwon-dev.java

@@ -0,0 +1,42 @@
+/**
+ *  시간 복잡도: O(n^2)
+ *  공간 복잡도: O(n)
+ */
+class Solution {
+    public List<List<Integer>> threeSum(int[] nums) {
+        int left, right, sum;
+        List<List<Integer>> results = new ArrayList<>();
+        Arrays.sort(nums);
+
+        for (int i = 0; i < nums.length - 2; i++) {
+            if (i > 0 && nums[i] == nums[i - 1]) {
+                continue;
+            }
+
+            left = i + 1;
+            right = nums.length - 1;
+
+            while (left < right) {
+                sum = nums[i] + nums[left] + nums[right];
+
+                if (sum < 0) {
+                    left++;
+                } else if (sum > 0) {
+                    right--;
+                } else {
+                    results.add(Arrays.asList(nums[i], nums[left], nums[right]));
+
+                    while (left < right && nums[left] == nums[left + 1]) {
+                        left++;
+                    }
+                    while (left < right && nums[right] == nums[right - 1]) {
+                        right--;
+                    }
+                    left++;
+                    right--;
+                }
+            }
+        }
+        return results;
+    }
+}