검지 Offer 알고리즘 실현의 23: 위에서 아래로 두 갈래 트리 인쇄

struct BinaryTreeNode {
    int m_nValue;
    BinaryTreeNode *m_pLeft;
    BinaryTreeNode *m_pRight;
};

#include <iostream>
#include <queue>
#include <cstring>
using namespace std;

struct BinaryTreeNode {
    int m_nValue;
    BinaryTreeNode *m_pLeft;
    BinaryTreeNode *m_pRight;
};

void printTreeBFS(BinaryTreeNode *pRoot)
{
    if (!pRoot) return;
    queue<BinaryTreeNode *>nodes;
    nodes.push(pRoot);
    while (!nodes.empty()) {
        BinaryTreeNode *pNode = nodes.front();
        cout << pNode->m_nValue << ' ';
        if (pNode->m_pLeft) nodes.push(pNode->m_pLeft);
        if (pNode->m_pRight) nodes.push(pNode->m_pRight);
        nodes.pop();
    }
}

/** 
 *  ( "1(2,3(,4))")  
 *  ：[start, end)
**/
BinaryTreeNode *createTree(const char *start, const char *end)
{
    if (start >= end) {
        return nullptr;
    }
    if (end - start == 1) {
        return new BinaryTreeNode{*start-'0', nullptr, nullptr};
    }
    const char *start1 = start+2;
    const char *end1 = start+2;
    int cnt = 0;
    while (true) {
        if (*end1 == '(') cnt++;
        if (*end1 == ')') cnt--;
        if (*end1 == ',' && cnt == 0) break;
        end1++;
    }
    const char *start2 = end1+1;
    const char *end2 = end1+1;
    cnt = 0;
    while (true) {
        if (*end2 == '(') cnt++;
        if (*end2 == ')' && cnt == 0) break;
        if (*end2 == ')') cnt--;
        end2++;
    }
    return new BinaryTreeNode{*start-'0', 
                    createTree(start1, end1),
                    createTree(start2, end2)};
}
/** Wrapper **/
BinaryTreeNode *createTree(const char *str)
{
    return createTree(str, str+strlen(str));
}
/**   **/
void printTree(BinaryTreeNode *pRoot){
    if (!pRoot) return;
    cout << pRoot->m_nValue;
    if (pRoot->m_pLeft || pRoot->m_pRight) cout << '(';
    if (pRoot->m_pLeft) {
        printTree(pRoot->m_pLeft);
    }
    if (pRoot->m_pLeft && pRoot->m_pRight) cout << ',';
    if (pRoot->m_pRight) {
        printTree(pRoot->m_pRight);
    }
    if (pRoot->m_pLeft || pRoot->m_pRight) cout << ')';
}

int main()
{
    BinaryTreeNode *pRoot = createTree("8(6(5,7),1(9,2))");
    printTree(pRoot); cout << endl;
    printTreeBFS(pRoot);
}