摘要：
Given a string with no duplicate characters, return a list with all permutations of the characters. Examples Set = “abc”, all permutations are [“abc”, 阅读全文
摘要：
Given a number of different denominations of coins (e.g., 1 cent, 5 cents, 10 cents, 25 cents), get all the possible ways to pay a target number of ce 阅读全文