zoukankan      html  css  js  c++  java
  • 【leetcode】944. Delete Columns to Make Sorted

    题目如下:

    We are given an array A of N lowercase letter strings, all of the same length.

    Now, we may choose any set of deletion indices, and for each string, we delete all the characters in those indices.

    For example, if we have a string "abcdef" and deletion indices {0, 2, 3}, then the final string after deletion is "bef".

    Suppose we chose a set of deletion indices D such that after deletions, each remaining column in A is in non-decreasing sorted order.

    Formally, the c-th column is [A[0][c], A[1][c], ..., A[A.length-1][c]]

    Return the minimum possible value of D.length.

    Example 1:

    Input: ["cba","daf","ghi"]
    Output: 1
    

    Example 2:

    Input: ["a","b"]
    Output: 0
    

    Example 3:

    Input: ["zyx","wvu","tsr"]
    Output: 3

    Note:

    1. 1 <= A.length <= 100
    2. 1 <= A[i].length <= 1000

    解题思路:如果不考虑时间复杂度,那么这题的级别应该是Easy,而不是Medium。O(n^2)的方法也很简单,遍历每一组序列,如果不满足递增则要删除这一组。

    代码如下:

    class Solution(object):
        def minDeletionSize(self, A):
            """
            :type A: List[str]
            :rtype: int
            """
            for i in range(len(A)):
                A[i] += '{'
            res = 0
            for j in range(len(A[0])):
                for i in range(len(A)-1):
                    if A[i][j] > A[i+1][j]:
                        res += 1
                        break
            return res
  • 相关阅读:
    学期总结
    C语言I博客作业09
    C语言I博客作业08
    C语言I博客作业07
    C语言I博客作业06
    C语言I博客作业05
    C语言II—作业04
    C语言II—作业03
    C语言II—作业02
    C语言II博客作业01
  • 原文地址:https://www.cnblogs.com/seyjs/p/9982856.html
Copyright © 2011-2022 走看看