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🐱(binary-search): 1095. 山脉数组中查找目标值

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docs/algorithm/research/binary-search
- README.md

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`‎docs/algorithm/research/binary-search/README.md‎`

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`@@ -718,4 +718,71 @@ func getMax(a int, b int) int {`
`718`	`718`	`}`
`719`	`719`	```
`720`	`720`
`721`		`-<!-- tabs:end -->`
	`721`	`+<!-- tabs:end -->`
	`722`	`+`
	`723`	`+## 1095. 山脉数组中查找目标值`
	`724`	`+`
	`725`	`+[原题链接](https://leetcode-cn.com/problems/find-in-mountain-array/)`
	`726`	`+`
	`727`	`+### 思路`
	`728`	`+`
	`729`	`+核心思想二分法:`
	`730`	`+`
	`731`	`+1. 通过二分法寻找峰值`
	`732`	`+2. 二分法在峰值左侧寻找目标`
	`733`	`+3. 如果目标不在左侧,使用二分法在峰值右侧寻找目标`
	`734`	`+`
	`735`	+```python
	`736`	`+# """`
	`737`	`+# This is MountainArray's API interface.`
	`738`	`+# You should not implement it, or speculate about its implementation`
	`739`	`+# """`
	`740`	`+#class MountainArray:`
	`741`	`+# def get(self, index: int) -> int:`
	`742`	`+# def length(self) -> int:`
	`743`	`+`
	`744`	`+class Solution:`
	`745`	`+ def findInMountainArray(self, target: int, mountain_arr: 'MountainArray') -> int:`
	`746`	`+ length = mountain_arr.length()`
	`747`	`+ # print(length)`
	`748`	`+ # 找到峰值`
	`749`	`+ left = 0`
	`750`	`+ right = length - 1`
	`751`	`+ while left < right:`
	`752`	`+ mid = (left + right) // 2`
	`753`	`+ if mountain_arr.get(mid + 1) > mountain_arr.get(mid):`
	`754`	`+ # 峰值在右侧`
	`755`	`+ left = mid + 1`
	`756`	`+ else:`
	`757`	`+ right = mid`
	`758`	`+ # 峰值`
	`759`	`+ peak = left`
	`760`	`+`
	`761`	`+ # 左侧二分查找`
	`762`	`+ left = 0`
	`763`	`+ right = peak`
	`764`	`+ while left <= right:`
	`765`	`+ mid = (left + right) // 2`
	`766`	`+ cur = mountain_arr.get(mid)`
	`767`	`+ if cur == target:`
	`768`	`+ return mid`
	`769`	`+ elif cur > target:`
	`770`	`+ right = mid - 1`
	`771`	`+ else:`
	`772`	`+ left = mid + 1`
	`773`	`+`
	`774`	`+ # 右边二分查找:递减数组`
	`775`	`+ left = peak + 1`
	`776`	`+ right = length - 1`
	`777`	`+ while left <= right:`
	`778`	`+ mid = (left + right) // 2`
	`779`	`+ cur = mountain_arr.get(mid)`
	`780`	`+ if cur == target:`
	`781`	`+ return mid`
	`782`	`+ elif cur > target:`
	`783`	`+ left = mid + 1`
	`784`	`+ else:`
	`785`	`+ right = mid - 1`
	`786`	`+`
	`787`	`+ return -1`
	`788`	+```

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