常用算法快速回顾

#include <cstdio>
#include <cstring>

char str[105];

struct Node {
    Node *lChild;
    Node *rChild;
    char d;
} Tree[105];
int pos;
int cur;

Node* BuildTree(int e) {
    if (str[cur] == ‘#‘ || cur >= e) return NULL;
    Tree[pos].lChild = Tree[pos].rChild = NULL;
    Node* root = &Tree[pos++];
    root->d = str[cur];
    ++cur;
    root->lChild = BuildTree(e);
    ++cur;
    root->rChild = BuildTree(e);
    return root;
}

void PrintTree(const Node* rt) {
    if(rt == NULL) return;
    if(rt->lChild != NULL) PrintTree(rt->lChild);
    printf("%c ", rt->d);
    if(rt->rChild != NULL) PrintTree(rt->rChild);
}

int main() {
#ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
#endif
    
    while (scanf("%s", str) != EOF) {
        pos = 0;
        cur = 0;
        Node* rt = BuildTree(strlen(str));
        PrintTree(rt);
        printf("\n");
    }

    return 0;
}