# [LeetCode]#2042. Check if Numbers Are Ascending in a Sentence

2 min readDec 16, 2021

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Environment: Python 3.8

Key technique: split, isdecimal, for, if, append

A sentence is a list of tokens separated by a single space with no leading or trailing spaces. Every token is either a positive number consisting of digits `0-9` with no leading zeros, or a word consisting of lowercase English letters.

• For example, `"a puppy has 2 eyes 4 legs"` is a sentence with seven tokens: `"2"` and `"4"` are numbers and the other tokens such as `"puppy"` are words.

Given a string `s` representing a sentence, you need to check if all the numbers in `s` are strictly increasing from left to right (i.e., other than the last number, each number is strictly smaller than the number on its right in `s`).

Return `true` if so, or `false` otherwise.

Example 1:

`Input: s = "1 box has 3 blue 4 red 6 green and 12 yellow marbles"Output: trueExplanation: The numbers in s are: 1, 3, 4, 6, 12.They are strictly increasing from left to right: 1 < 3 < 4 < 6 < 12.`

Analysis:

1. Use split to get each word such as “1”, “box”….
2. Use isdecimal to judge it is number or not.
3. If yes, add it to list. If not, skip it.
4. If list[t] ≥ list[t+1], return False. Else, return True.

Solution:

`class Solution:    def areNumbersAscending(self, s):ans=[]        for s in s.split():            if not s.isdecimal():                continue            else:                ans.append(int(s))        #sans=sorted(ans)        for i in range(len(ans)-1):            if ans[i]>=ans[i+1]:                return False                                 return True`

Submissions:

Reference:

https://leetcode.com/problems/check-if-numbers-are-ascending-in-a-sentence/discuss/1596791/Simple-and-Easy-Solution-by-Python-3