From 980fa06605e73c5a47d690c6f70852d1d5498b1e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9D=8E=E6=9F=8F=E6=9E=97?=
 <37291290+luckydog612@users.noreply.github.com>
Date: Tue, 30 Oct 2018 11:03:47 +0800
Subject: [PATCH] Create binarysearch2.go
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

16 | 二分查找（下）
---
 go/binarysearch2.go | 90 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 go/binarysearch2.go

diff --git a/go/binarysearch2.go b/go/binarysearch2.go
new file mode 100644
index 0000000..ef2549e
--- /dev/null
+++ b/go/binarysearch2.go
@@ -0,0 +1,90 @@
+package binarySearch
+
+//查找第一个值等于给定值得元素
+func BinarySearch2(nums []int, value int) int {
+	length := len(nums)
+	start := 0
+	end := length - 1
+	for start <= end {
+		mid := (start + end) / 2
+		if nums[mid] > value {
+			end = mid - 1
+		} else if nums[mid] < value {
+			start = mid + 1
+		} else {
+			for mid >= 0 {
+				if nums[mid-1] == value {
+					mid--
+				} else {
+					return mid
+				}
+			}
+		}
+	}
+	return -1
+}
+
+// 查找最后一个值等于给定值的元素
+func BinarySearch3(nums []int, value int) int {
+	start := 0
+	end := len(nums) - 1
+	for start <= end {
+		mid := (start + end) / 2
+		if nums[mid] > value {
+			end = mid - 1
+		} else if nums[mid] < value {
+			start = mid + 1
+		} else {
+			for mid < len(nums) {
+				if nums[mid+1] == value {
+					mid++
+				} else {
+					return mid
+				}
+			}
+		}
+	}
+	return -1
+}
+
+// 查找第一个大于等于给定值的元素
+func BinarySearch4(nums []int, value int) int {
+	start := 0
+	end := len(nums) - 1
+	for start <= end {
+		mid := (start + end) >> 1
+		if nums[mid] < value {
+			start = mid + 1
+		} else {
+			for mid >= 0 {
+				if nums[mid-1] >= value {
+					mid--
+				} else {
+					return mid
+				}
+			}
+		}
+	}
+	return -1
+}
+
+// 查找最后一个小于等于给定值的元素
+func BinarySearch5(nums []int, value int) int {
+	start := 0
+	end := len(nums) - 1
+	for start <= end {
+		mid := (start + end) >> 1
+		if nums[mid] > value {
+			end = mid - 1
+		} else {
+			for mid < len(nums) {
+				if nums[mid+1] <= value {
+					mid++
+				} else {
+					return mid
+				}
+			}
+		}
+	}
+	return -1
+}