摘要：
Crossing BridgeDescriptionN people wish to cross a bridge at night. It’s so dark around there that they have to cross the bridge under the help of a l... 阅读全文
摘要：
N-QueensThe n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.Given an integer n, retu... 阅读全文