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feat: add solutions to lcof2 problem: No.007
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‎lcof2/剑指 Offer II 007. 数组中和为 0 的三个数/README.md

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<!-- 这里可写通用的实现逻辑 -->
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枚举第一个数，然后用双指针确定另外两个数
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def threeSum(self, nums: List[int]) -> List[List[int]]:
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n, ans = len(nums), []
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nums.sort()
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for i in range(n - 2):
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if i > 0 and nums[i] == nums[i - 1]: continue
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left, right = i + 1, n - 1
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while left < right:
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cur = nums[i] + nums[left] + nums[right]
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if cur < 0:
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left += 1
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elif cur > 0:
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right -= 1
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else:
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ans.append([nums[i], nums[left], nums[right]])
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while left < right and nums[left] == nums[left + 1]:
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left += 1
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while left < right and nums[right] == nums[right - 1]:
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right -= 1
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left += 1
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right -= 1
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return ans
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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public List<List<Integer>> threeSum(int[] nums) {
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int n = nums.length;
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List<List<Integer>> ans = new ArrayList<>();
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Arrays.sort(nums);
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for (int i = 0; i < n - 2; i++) {
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if (i > 0 && nums[i] == nums[i - 1]) {
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continue;
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}
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int left = i + 1, right = n - 1;
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while (left < right) {
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int cur = nums[i] + nums[left] + nums[right];
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if (cur < 0) {
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left++;
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} else if (cur > 0) {
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right--;
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} else {
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ans.add(Arrays.asList(nums[i], nums[left], nums[right]));
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while (left < right && nums[left] == nums[left + 1]) {
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left++;
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}
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while (left < right && nums[right] == nums[right - 1]) {
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right--;
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}
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left++;
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right--;
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}
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}
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}
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return ans;
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}
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}
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```
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### **Go**
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```go
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func threeSum(nums []int) [][]int {
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n := len(nums)
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ans := make([][]int, 0)
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sort.Ints(nums)
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for i := 0; i < n-2 && nums[i] <= 0; i++ {
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left, right := i+1, n-1
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for left < right {
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cur := nums[i] + nums[left] + nums[right]
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if cur < 0 {
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left++
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} else if cur > 0 {
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right--
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} else {
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ans = append(ans, []int{nums[i], nums[left], nums[right]})
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for left < right && nums[left] == nums[left+1] {
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left++
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}
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for left < right && nums[right] == nums[right-1] {
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right--
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}
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left++
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right--
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}
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}
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for i < n-2 && nums[i] == nums[i+1] {
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i++
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}
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}
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return ans
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}
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```
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### **...**

‎lcof2/剑指 Offer II 007. 数组中和为 0 的三个数/Solution.go

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func threeSum(nums []int) [][]int {
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n := len(nums)
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ans := make([][]int, 0)
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sort.Ints(nums)
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for i := 0; i < n-2 && nums[i] <= 0; i++ {
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left, right := i+1, n-1
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for left < right {
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cur := nums[i] + nums[left] + nums[right]
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if cur < 0 {
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left++
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} else if cur > 0 {
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right--
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} else {
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ans = append(ans, []int{nums[i], nums[left], nums[right]})
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for left < right && nums[left] == nums[left+1] {
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left++
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}
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for left < right && nums[right] == nums[right-1] {
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right--
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}
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left++
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right--
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}
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}
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for i < n-2 && nums[i] == nums[i+1] {
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i++
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}
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}
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return ans
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}

‎lcof2/剑指 Offer II 007. 数组中和为 0 的三个数/Solution.java

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class Solution {
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public List<List<Integer>> threeSum(int[] nums) {
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int n = nums.length;
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List<List<Integer>> ans = new ArrayList<>();
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Arrays.sort(nums);
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for (int i = 0; i < n - 2; i++) {
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if (i > 0 && nums[i] == nums[i - 1]) {
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continue;
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}
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int left = i + 1, right = n - 1;
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while (left < right) {
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int cur = nums[i] + nums[left] + nums[right];
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if (cur < 0) {
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left++;
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} else if (cur > 0) {
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right--;
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} else {
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ans.add(Arrays.asList(nums[i], nums[left], nums[right]));
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while (left < right && nums[left] == nums[left + 1]) {
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left++;
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}
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while (left < right && nums[right] == nums[right - 1]) {
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right--;
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}
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left++;
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right--;
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}
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}
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}
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return ans;
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}
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}

‎lcof2/剑指 Offer II 007. 数组中和为 0 的三个数/Solution.py

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class Solution:
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def threeSum(self, nums: List[int]) -> List[List[int]]:
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n, ans = len(nums), []
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nums.sort()
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for i in range(n - 2):
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if i > 0 and nums[i] == nums[i - 1]: continue
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left, right = i + 1, n - 1
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while left < right:
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cur = nums[i] + nums[left] + nums[right]
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if cur < 0:
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left += 1
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elif cur > 0:
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right -= 1
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else:
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ans.append([nums[i], nums[left], nums[right]])
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while left < right and nums[left] == nums[left + 1]:
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left += 1
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while left < right and nums[right] == nums[right - 1]:
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right -= 1
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left += 1
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right -= 1
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return ans

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