1 void PreOrderRec(int x)//x为根节点
2 {
3 if (x == 0)return;//若遍历完成，返回函数
4 PreOrderRec(a[x].left);//遍历左孩子
5 PreOrderRec(a[x].right);//遍历右孩子
6 cout<<x;
7 }
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