PAT甲题题解-1130. Infix Expression (25)-中序遍历

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <string>
#include <vector>
#include <cstring>
#include <queue>
using namespace std;
const int maxn=25;
int n;
struct Node{
    char str[15];
    int left;
    int right;
}node[maxn];


void dfs(int u,int root){
    if(node[u].left==-1 && node[u].right==-1){
        printf("%s",node[u].str);
        return;
    }
    if(u!=root)
        printf("(");
    if(node[u].left!=-1)
        dfs(node[u].left,root);
    printf("%s",node[u].str);
    if(node[u].right!=-1)
        dfs(node[u].right,root);
    if(u!=root)
        printf(")");
}
int main()
{
    char s[15];
    int l,r;
    int vis[maxn];
    memset(vis,0,sizeof(vis));
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        scanf("%s %d %d",node[i].str,&l,&r);
        node[i].left=l;
        node[i].right=r;
        vis[l]=vis[r]=1;
    }
    int root;
    for(int i=1;i<=n;i++){
        if(!vis[i]){
            root=i;
            break;
        }
    }
    dfs(root,root);
    return 0;
}