子串：

• 003-longest substring without repeating characters
• 014-longest common prefix
• 028-implement stlstr()
• 030-substring with concatenation of all words
• 058-length of last words
• 076-minimum windows substring

回文字符

• 005-longest palindromic substring
• 115-valid palindeome
• 214-shortest palindrome
• 336-palindrome pair

字符读法

• 008-string to integer
• 012-integer to roman
• 013-roman to integer
• 273-integer to english words

字符匹配

• 010-regular expression matching
• 044-wildcard matching
• 072-edit distance
• 020-valid parentheses
• 022-generate parentheses
• 032-longest valid parentheses
• 006-zigzag conversion
• 068-text justification
• 165-compare version numbers
• 224-basic calculator
• 227-basic calculatorII

字符排序

• 017-letter combinations of a phone number
• 049-group anagrams

字符串运算

• 043-multiply strings
• 067-add binary

字符串变换

• 038-count and say
• 065-valid number
• 071- simplify path
• 087-scramble string
• 091-decode ways
• 093-restore ip address
• 097-interleaving string
• 115-disitinct subsequences
• 151-reverse words in a string
• 344-reverse string
• 345-resverse vowels of string