摘要：
Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix, return an empty string "". Input: 阅读全文
摘要：
Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. For example, 2 is written as II in Roman numeral, just two one's ad 阅读全文
摘要：
Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. For example, 2 is written as II in Roman numeral, just two one's ad 阅读全文
摘要：
Given n non-negative integers a1, a2, ..., an , where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endp 阅读全文