Leetcode 34 Search for a Range

Andrew9tech

于 2015-05-21 11:55:59 发布

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分类专栏： Leetcode刷题

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本文详细介绍了使用二分查找法解决搜索范围问题的方法，包括实现细节与优化技巧。

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class Solution:
    # @param {integer[]} nums
    # @param {integer} target
    # @return {integer[]}
    def searchRange(self, nums, target):
        if target in nums:
            result = []
            start = nums.index(target)
            result.append(start)
            times = nums.count(target)
            result.append(start+times-1)
            return result
        else:
            return [-1, -1]

二分查找法：

class Solution:
    # @param {integer[]} nums
    # @param {integer} target
    # @return {integer[]}
    def searchRange(self, nums, target):
        left, right = 0, len(nums)-1  
        while left <= right:  
            mid = (left + right)/2  
            if  target < nums[mid]:  
                right = mid-1  
            elif target > nums[mid]:  
                left = mid+1 
            else:
                result = [0, 0]
                if nums[left] == target: result[0] = left
                if nums[right] == target: result[1] = right
                for i in xrange(mid, right+1):
                    if nums[i] != target: result[1] = i - 1; break
                for j in xrange(mid, left-1, -1):
                    if nums[j] != target: result[0] = j + 1; break
                return result
        return [-1, -1]