《Cracking the Coding Interview》——第8章：面向对象设计——题目6

2014-04-23 22:57

题目：实现一个数据结构来表示拼图游戏中的碎片。

解法：一个拼图块儿有四条边，每边只有凹凸平三种情况，当两块碎片拼接的时候，分为四个方向进行，块儿上的图案肯定也是判断是否能拼接的依据之一。所以就有了以下的表示方法，又一题做得云里雾里。话说这种题目在面试时如果真遇到，得写到什么程度的代码才算及格？

代码：

// 8.6 Design data structure to represent pieces in jigsaw puzzle. If possible please design an algorithm to solve it.
// I'll use the struct below to represent a piece, which has four sides, each one of which is either concave, convex or plain.
// And they must have some patterns on them, which can be considered as images.
// Solving a jigsaw can be done with DFS, which can be O(n!) in time scale, where n is total number of pieces.
// A possibl way is to do it in diagonal manner, starting from the left top corner.
// Like this:
// 0 1 2 3
// 1 2 3 .
// 2 3 ...
// 3 .....
// When doing the search, you have to check if a piece can be fit into a targetted position.
// a method fitsWith() will be used, parameters will included two pieces and a direction.
// For example, fitsWith(piece1, piece2, BOTTOM) means if piece2 fits on the bottom of piece1.
struct JigsawPuzzlePiece {
    // left, top, right, bottom
    // -1 for concave, +1 for convex, 0 for plain
    int side[4];
    Image *image;
};