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add 二分查找详解code in Go

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lincongcong 2021-07-19 14:33:01 +08:00
parent b46603ce37
commit a177043d3f
1 changed files with 83 additions and 31 deletions
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112
animation-simulation/二分查找及其变种/二分查找详解.md
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@ -118,27 +118,54 @@ target < nums[mid] 则在左半区间继续进行搜索，即 right = mid -1；
下面我们来看一下二分查找的代码，可以认真思考一下 if 语句的条件，每个都没有简写。
Java Code:
```java
public static int binarySearch(int[] nums,int target,int left, int right) {
//这里需要注意，循环条件
while (left <= right) {
//这里需要注意，计算mid
int mid = left + ((right - left) >> 1);
if (nums[mid] == target) {
return mid;
}else if (nums[mid] < target) {
//这里需要注意，移动左指针
left = mid + 1;
}else if (nums[mid] > target) {
//这里需要注意，移动右指针
right = mid - 1;
}
public static int binarySearch(int[] nums,int target,int left, int right) {
//这里需要注意，循环条件
while (left <= right) {
//这里需要注意，计算mid
int mid = left + ((right - left) >> 1);
if (nums[mid] == target) {
return mid;
}else if (nums[mid] < target) {
//这里需要注意，移动左指针
left = mid + 1;
}else if (nums[mid] > target) {
//这里需要注意，移动右指针
right = mid - 1;
}
//没有找到该元素，返回 -1
return -1;
}
//没有找到该元素，返回 -1
return -1;
}
```
Go Code:
```go
func binarySearch(nums []int, target, left, right int) int {
//这里需要注意，循环条件
for left <= right {
//这里需要注意，计算mid
mid := left + ((right - left) >> 1)
if nums[mid] == target {
return mid
} else if nums[mid] < target {
//这里需要注意，移动左指针
left = mid + 1
} else if nums[mid] > target {
//这里需要注意，移动右指针
right = mid - 1
}
}
//没有找到该元素，返回 -1
return -1
}
```
二分查找的思路及代码已经理解了，那么我们来看一下实现时容易出错的地方
@ -155,25 +182,50 @@ target < nums[mid] 则在左半区间继续进行搜索，即 right = mid -1；
下面我们来看一下二分查找的递归写法
Java Code:
```java
public static int binarySearch(int[] nums,int target,int left, int right) {
if (left <= right) {
int mid = left + ((right - left) >> 1);
if (nums[mid] == target) {
//查找成功
return mid;
}else if (nums[mid] > target) {
//新的区间,左半区间
return binarySearch(nums,target,left,mid-1);
}else if (nums[mid] < target) {
//新的区间，右半区间
return binarySearch(nums,target,mid+1,right);
}
if (left <= right) {
int mid = left + ((right - left) >> 1);
if (nums[mid] == target) {
//查找成功
return mid;
}else if (nums[mid] > target) {
//新的区间,左半区间
return binarySearch(nums,target,left,mid-1);
}else if (nums[mid] < target) {
//新的区间，右半区间
return binarySearch(nums,target,mid+1,right);
}
//不存在返回-1
return -1;
}
//不存在返回-1
return -1;
}
```
Go Code:
```go
func binarySearch(nums []int, target, left, right int) int {
if left <= right {
mid := left + ((right - left) >> 1)
if nums[mid] == target {
//查找成功
return mid
} else if nums[mid] > target {
//新的区间,左半区间
return binarySearch(nums, target, left, mid-1)
} else if nums[mid] < target {
//新的区间，右半区间
return binarySearch(nums, target, mid+1, right)
}
}
//不存在返回-1
return -1
}
```