Merge pull request #227 from gostool/leetcode0540

Leetcode0540

leetcode/0540.Single-Element-in-a-Sorted-Array/540.Single Element in a Sorted Array.go

@@ -0,0 +1,22 @@
+package leetcode
+
+func singleNonDuplicate(nums []int) int {
+	left, right := 0, len(nums)-1
+	for left < right {
+		mid := (left + right) / 2
+		if mid%2 == 0 {
+			if nums[mid] == nums[mid+1] {
+				left = mid + 1
+			} else {
+				right = mid
+			}
+		} else {
+			if nums[mid] == nums[mid-1] {
+				left = mid + 1
+			} else {
+				right = mid
+			}
+		}
+	}
+	return nums[left]
+}

leetcode/0540.Single-Element-in-a-Sorted-Array/540.Single Element in a Sorted Array_test.go

@@ -0,0 +1,46 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question540 struct {
+	para540
+	ans540
+}
+
+// para 是参数
+type para540 struct {
+	nums []int
+}
+
+// ans 是答案
+type ans540 struct {
+	ans int
+}
+
+func Test_Problem540(t *testing.T) {
+
+	qs := []question540{
+
+		{
+			para540{[]int{1, 1, 2, 3, 3, 4, 4, 8, 8}},
+			ans540{2},
+		},
+
+		{
+			para540{[]int{3, 3, 7, 7, 10, 11, 11}},
+			ans540{10},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 540------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans540, q.para540
+		fmt.Printf("【input】:%v      ", p.nums)
+		fmt.Printf("【output】:%v      \n", singleNonDuplicate(p.nums))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/0540.Single-Element-in-a-Sorted-Array/README.md

@@ -0,0 +1,64 @@
+# [540. Single Element in a Sorted Array](https://leetcode-cn.com/problems/single-element-in-a-sorted-array/)
+
+## 题目
+
+You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once.
+
+Return the single element that appears only once.
+
+Your solution must run in O(log n) time and O(1) space.
+
+**Example 1:**
+
+    Input: nums = [1,1,2,3,3,4,4,8,8]
+    Output: 2
+
+**Example 2:**
+
+    Input: nums = [3,3,7,7,10,11,11]
+    Output: 10
+
+**Constraints:**
+
+- 1 <= nums.length <= 100000
+- 0 <= nums[i] <= 100000
+
+## 题目大意
+
+给你一个仅由整数组成的有序数组，其中每个元素都会出现两次，唯有一个数只会出现一次。
+
+请你找出并返回只出现一次的那个数。
+
+你设计的解决方案必须满足 O(log n) 时间复杂度和 O(1) 空间复杂度。
+
+## 解题思路
+
+    假设下标idx是单独的数字,idx左边的偶数下标x有nums[x] == nums[x + 1],
+    idx右边的奇数下标y有nums[y] == nums[y + 1],可以根据此特性用二分查找idx对应的值 
+
+## 代码
+
+```go
+package leetcode
+
+func singleNonDuplicate(nums []int) int {
+	left, right := 0, len(nums)-1
+	for left < right {
+		mid := (left + right) / 2
+		if mid%2 == 0 {
+			if nums[mid] == nums[mid+1] {
+				left = mid + 1
+			} else {
+				right = mid
+			}
+		} else {
+			if nums[mid] == nums[mid-1] {
+				left = mid + 1
+			} else {
+				right = mid
+			}
+		}
+	}
+	return nums[left]
+}
+```