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LintCode 49 Sort Letters By Case - Medium

49. Sort Letters by Case

·1 min read·#LintCode#Medium#Python

49. Sort Letters By Case — Medium

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Problem

  1. Sort Letters by Case

Given a string which contains only letters. Sort it by lower case first and upper case second.

Example Example 1: Input: "abAcD" Output: "acbAD"

Example 2: Input: "ABC" Output: "ABC"

Challenge Do it in one-pass and in-place.

Notice It's NOT necessary to keep the original order of lower-case letters and upper case letters.

Solution

class Solution:
    """
    @param: chars: The letter array you should sort by Case
    @return: nothing
    """
    def sortLetters(self, chars):
        # write your code here
        # 定义左右指针并初始化
        left = 0
        right = len(chars) - 1
 
        # 两指针相向移动，交会则结束
        while left <= right:
            # 左指针向右移动，直到找到第一个大写字母
            while left <= right and chars[left] >= 'a' and chars[left] <= 'z':
                left += 1
 
            # 右指针向左移动，直到找到第一个小写字母
            while left <= right and chars[right] >= 'A' and chars[right] <= 'Z':
                right -= 1
 
            # 将左边的大写字母和右边的小写字母交换位置
            if left <= right:
                tmp = chars[left]
                chars[left] = chars[right]
                chars[right] = tmp
                left += 1
                right -= 1

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