zeng1qing2rong3的博客

描述： Roman numerals are represented by seven different symbols:I,V,X,L,C,DandM. Symbol Value I 1 V 5 X 10 L 50 C 100 D ...

描述： Given a string containing just the characters'(',')','{','}','['and']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same typ...

描述： Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists. Example: Input: 1->2->4, 1->3->4 Outp...