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### 题目描述

You are given a string `s` and an array of strings `words` of the same length. Return all starting indices of substring(s) in `s` that is a concatenation of each word in `words` exactly once, in any order, and without any intervening characters.

You can return the answer in any order.

### 题目描述

Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).

### 题目描述

Validate if a given string can be interpreted as a decimal number.

## 简介

• 析构函数绝对不要抛出异常。如果一个被析构函数调用的函数可能抛出异常，则在析构函数捕捉它并主动终止程序或不作处理；
• 如果使用者需要对该异常进行处理，那么类中应该提供一个普通函数执行该操作。

## 概述

### 题目描述

Given an array of words and a width maxWidth, format the text such that each line has exactly maxWidth characters and is fully (left and right) justified.

You should pack your words in a greedy approach; that is, pack as many words as you can in each line. Pad extra spaces `' '` when necessary so that each line has exactly maxWidth characters.

Extra spaces between words should be distributed as evenly as possible. If the number of spaces on a line do not divide evenly between words, the empty slots on the left will be assigned more spaces than the slots on the right.

For the last line of text, it should be left justified and no extra space is inserted between words.

## 课程简介

### 题目描述

Roman numerals are represented by seven different symbols: `I`, `V`, `X`, `L`, `C`, `D` and `M`.

Symbol Value
I 1
V 5
X 10
L 50
C 100
D 500
M 1000
For example, two is written as `II` in Roman numeral, just two one’s added together. Twelve is written as, `XII`, which is simply `X` + `II`. The number twenty seven is written as `XXVII`, which is `XX + V + II`.

Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not `IIII`. Instead, the number four is written as IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used:

I can be placed before `V` (5) and `X` (10) to make 4 and 9.
X can be placed before `L` (50) and `C` (100) to make 40 and 90.
C can be placed before `D` (500) and `M` (1000) to make 400 and 900.
Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.

### 题目描述

Roman numerals are represented by seven different symbols: `I`, `V`, `X`, `L`, `C`, `D` and `M`.

Symbol Value
I 1
V 5
X 10
L 50
C 100
D 500
M 1000
For example, two is written as `II` in Roman numeral, just two one’s added together. Twelve is written as, `XII`, which is simply `X` + `II`. The number twenty seven is written as `XXVII`, which is `XX + V + II`.

Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not `IIII`. Instead, the number four is written as IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used:

I can be placed before `V` (5) and `X` (10) to make 4 and 9.
X can be placed before `L` (50) and `C` (100) to make 40 and 90.
C can be placed before `D` (500) and `M` (1000) to make 400 and 900.
Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999.

### 题目描述

Given a positive integer, return its corresponding column title as appear in an Excel sheet.

For example:

1 -> A
2 -> B
3 -> C

26 -> Z
27 -> AA
28 -> AB