From 93cbd6955ca70ceddcc55026b55cf991db00bd81 Mon Sep 17 00:00:00 2001
From: whai <lkwhai@163.com>
Date: Wed, 3 Jan 2024 22:13:32 +0800
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---
 .../cn/whaifree/leetCode/Hash/LeetCode15.java | 68 +++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 src/main/java/cn/whaifree/leetCode/Hash/LeetCode15.java

diff --git a/src/main/java/cn/whaifree/leetCode/Hash/LeetCode15.java b/src/main/java/cn/whaifree/leetCode/Hash/LeetCode15.java
new file mode 100644
index 0000000..2539acf
--- /dev/null
+++ b/src/main/java/cn/whaifree/leetCode/Hash/LeetCode15.java
@@ -0,0 +1,68 @@
+package cn.whaifree.leetCode.Hash;
+
+import org.junit.Test;
+
+import java.util.*;
+import java.util.function.Consumer;
+
+public class LeetCode15 {
+
+    @Test
+    public void test() {
+        new Solution().threeSum(new int[]{-1, 0, 1, 2, -1, -4}).forEach(integers -> {
+            System.out.println();
+            integers.forEach(
+                    integer -> System.out.print(integer + " ")
+            );
+        });
+    }
+
+    class Solution {
+        /**
+         * TODO 2024-1-3 用三指针，没做出来
+         * @param nums
+         * @return
+         */
+        public List<List<Integer>> threeSum(int[] nums) {
+            Arrays.sort(nums);
+            List<List<Integer>> o = new ArrayList<>();
+            // 排序后第一个就大于0，必然不可能有结果
+            if (nums[0] > 0) {
+                return o;
+            }
+            for (int i = 0; i < nums.length; i++) {
+
+                int left = i + 1;
+                int right = nums.length - 1;
+
+                // 如果前后两个i 相同，跳过
+                if (i > 0 && nums[i] == nums[i - 1]) {  // 去重a
+                    continue;
+                }
+
+                while (left < right) {
+                    int number = nums[i] + nums[right] + nums[left];
+                    if (number > 0) {
+                        right--;
+                    } else if (number < 0) {
+                        left++;
+                    } else {
+                        o.add(Arrays.asList(nums[i], nums[left], nums[right]));
+                        // 去重逻辑应该放在找到一个三元组之后，对b 和 c去重
+                        // 如果 right左边的两个一样，去重，跳过去，但依然要保证要比left大
+                        while (right > left && nums[right] == nums[right - 1]){
+                            right--;
+                        }
+                        while (right > left && nums[left] == nums[left + 1]) {
+                            left++;
+                        }
+                        right--;
+                        left++;
+                    }
+                }
+
+            }
+            return o;
+        }
+    }
+}