MOOC 3.3 小白专场 树的同构

// 树的同构
/*
	1. 二叉树的表示
	2. 建二叉树
	3. 同构判别
*/

// 1. 二叉树的表示
// 结构数组表示二叉树: 静态链表
#define MaxTree 10
#define ElementType char
#define Tree int
#define Null -1

struct TreeNode 
{
	ElementType Element;
	Tree Left;
	Tree Right;
}T1[MaxTree], T2[MaxTree];

// 程序框架搭建
int main()
{
	Tree R1, R2;
	
	R1 = BuildTree(T1);
	R2 = BuildTree(T2);
	if(Isomorphic(R1, R2))	printf("Yes\n");
	else	printf("No\n");
	
	return 0;
} 

// 如何建立二叉树
Tree BuildTree(struct TreeNode T[])
{
	...
	scanf("%d\n", &N);
	if(N)
	{
		for(i = 0; i < N; ++ i)	check[i] = 0;
		for(i = 0; i < N; ++ i)	
		{
			scanf("%c %c %c\n", &T[i].Element, &cl, &cr);
			/* 对cl的对应处理 */ 
			if(cl != '-')
			{
				T[i].Left = cl - '0';
				check[T[i].Left] = 1;
			}
			else	T[i].Left = Null;
			/* 对cr的对应处理 */ 
			if(cr != '-')
			{
				T[i].Right = cr - '0';
				check[T[i].Right] = 1;
			}
			else	T[i].Right = Null;
		}
		for(i = 0; i < N; ++ i)
			if(!check[i])	break;
		Root = i;
	}
	return Root;
} 

int Isomorphic(Tree R1, Tree R2)
{
	/* both empty */
	if((R1 == Null) && (R2 == Null))
		return 1;
	/* one of them is empty */
	if(((R1 == Null) && (R2 != Null)) || ((R1 != Null) && R2 == Null))
		return 0;
	/* roots are different */
	if(T1[R1].Element != T2[R2].Element)
		return 0;
	/* both have no left subtree */
	if((T1[R1].Left == Null) && (T2[R2].Left == Null))
		return Isomorphic(T1[R1].Right, T2[R2].Right);
	/* no need to swap the left and the right */
	if(((T1[R1].Left != Null) && (T2[R2].Left != Null)) &&
	((T1[T1[R1].Left].Element) == (T2[T2[R2].Left].Element)))
		return (Isomorphic(T1[R1].Left, T2[R2].Left) && 
				Isomorphic(T1[R1].Right, T2[R2].Right));
	else
		return (Isomorphic(T1[R1].Left, T2[R2].Right) &&
				Isomorphic(T1[R1].Right, T2[R2].Left));
}