添加 34. 在排序数组中查找元素的第一个和最后一个位置 Go版本

problems/0034.在排序数组中查找元素的第一个和最后一个位置.md

@@ -389,6 +389,54 @@ class Solution:
 ### Go
 
 ```go
+func searchRange(nums []int, target int) []int {
+	leftBorder := searchLeftBorder(nums, target)
+	rightBorder := searchRightBorder(nums, target)
+
+	if leftBorder == -2 || rightBorder == -2 { // 情况一
+		return []int{-1, -1}
+	} else if rightBorder-leftBorder > 1 { // 情况三
+		return []int{leftBorder + 1, rightBorder - 1}
+	} else { // 情况二
+		return []int{-1, -1}
+	}
+}
+
+func searchLeftBorder(nums []int, target int) int {
+	left, right := 0, len(nums)-1
+	leftBorder := -2 // 记录一下leftBorder没有被赋值的情况
+	for left <= right {
+		middle := (left + right) / 2
+		if target == nums[middle] {
+			right = middle - 1
+			// 左边界leftBorder更新
+			leftBorder = right
+		} else if target > nums[middle] {
+			left = middle + 1
+		} else {
+			right = middle - 1
+		}
+	}
+	return leftBorder
+}
+
+func searchRightBorder(nums []int, target int) int {
+	left, right := 0, len(nums)-1
+	rightBorder := -2 // 记录一下rightBorder没有被赋值的情况
+	for left <= right {
+		middle := (left + right) / 2
+		if target == nums[middle] {
+			left = middle + 1
+			// 右边界rightBorder更新
+			rightBorder = left
+		} else if target > nums[middle] {
+			left = middle + 1
+		} else {
+			right = middle - 1
+		}
+	}
+	return rightBorder
+}
 ```
 
 ### JavaScript