# LeetCode 10. Regular Expression Matching

Regular Expression Matching

## Description

Implement regular expression matching with support for ‘.’ and ‘*'.

``````'.' Matches any single character.
'*' Matches zero or more of the preceding element.

The matching should cover the entire input string (not partial).

The function prototype should be:
bool isMatch(const char *s, const char *p)

Some examples:
isMatch("aa","a") → false
isMatch("aa","aa") → true
isMatch("aaa","aa") → false
isMatch("aa", "a*") → true
isMatch("aa", ".*") → true
isMatch("ab", ".*") → true
isMatch("aab", "c*a*b") → true
``````

# LeetCode 9. Palindrome Number

Palindrome Number

## Description

Determine whether an integer is a palindrome. Do this without extra space.

# LeetCode 8. String to Integer (atoi)

String to Integer (atoi)

## Description

Implement atoi to convert a string to an integer. Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the > possible input cases. Notes: It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the > input requirements up front.

# LeetCode 7. Reverse Integer

Reverse Integer

## Description

Reverse digits of an integer. `Example1: x = 123, return 321` `Example2: x = -123, return -321` The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reversed integer overflows.

# LeetCode 6. ZigZag Conversion

ZigZag Conversion

## Description

The string `"PAYPALISHIRING"` is written in a zigzag pattern on a given number of rows like this: (you may want to display this > pattern in a fixed font for better legibility)

``````P   A   H   N
A P L S I I G
Y   I   R
``````

And then read line by line: `"PAHNAPLSIIGYIR"`

Write the code that will take a string and make this conversion given a number of rows:

``string convert(string text, int nRows);``

`convert("PAYPALISHIRING", 3)` should return `"PAHNAPLSIIGYIR"`.

# LeetCode 5. Longest Palindromic Substring

Longest Palindromic Substring

## Description

Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000.

Example:

``````Input: "babad"
Output: "bab"
``````

Note: “aba” is also a valid answer.

Example:

``````Input: "cbbd"
Output: "bb"
``````

# LeetCode 4. Median of Two Sorted Arrays

Median of Two Sorted Arrays

## Description

There are two sorted arrays nums1 and nums2 of size m and n respectively.

Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).

Example 1:

``````nums1 = [1, 3]
nums2 = [2]
``````

The median is 2.0 Example 2:

``````nums1 = [1, 2]
nums2 = [3, 4]
``````

The median is (2 + 3)/2 = 2.5

# LeetCode 3. Longest Substring Without Repeating Characters

Longest Substring Without Repeating Characters

## Description

Given a string, find the length of the longest substring without repeating characters.

Given “abcabcbb”, the answer is “abc”, which the length is 3.

Given “bbbbb”, the answer is “b”, with the length of 1.

Given “pwwkew”, the answer is “wke”, with the length of 3. Note that the answer must be a substring, “pwke” is a subsequence and not a substring.

Programer

ChengDu·China