3Sum 문제

Author: ymir0804

3sum/ymir0804.java

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+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+class Solution {
+    public List<List<Integer>> threeSum(int[] nums) {
+        List<List<Integer>> answer = new ArrayList<>();
+        Arrays.sort(nums);
+        int sum = 0;
+
+        for (int i = 0; i < nums.length-2; i++) {
+            int left = i + 1;
+            int right = nums.length -1;
+            if(i > 0 && nums[i-1] == nums[i]) {
+                continue;
+            }
+            while (left < right ) {
+                sum = nums[i] + nums[left] + nums[right];
+                if(sum > 0) {
+                    right--;
+                } else if(sum < 0 ) {
+                    left++;
+                } else {
+                    answer.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 answer;
+    }
+}