50247. Build a Boolean Expression Tree

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "buildTree.h"
 
typedef struct{
    Node* val;
    int end_idx;
} info;
 
Node* new_node(char* c){
    Node* n = (Node*) malloc(sizeof(Node));
    n->val = c;
    n->left = NULL, n->right = NULL;
    return n;
}
 
info dfs(char* arr[], int l, int n){
    if(arr[l][0] == '!'){
        info next_info = dfs(arr, l + 1, n);
        Node* this_node = new_node(arr[l]);
        this_node->left = next_info.val;
        this_node->right = NULL;
        return (info) {this_node, next_info.end_idx};
    }
    else if(arr[l][0] == '('){
        info left_info = dfs(arr, l + 1, n);
        info right_info = dfs(arr, left_info.end_idx + 1, n);
 
        Node* this_node = new_node(arr[left_info.end_idx]);
        this_node->left = left_info.val;
        this_node->right = right_info.val;
        return (info) {this_node, right_info.end_idx + 1};
    }
    else {
        return (info) {new_node(arr[l]), l + 1};
    }
}
 
Node* buildTree(char* s){
    char* exp[500005]; int n = 0;
    char *token = strtok(s, " ");
    while(token != NULL){
        exp[n++] = token;
        token = strtok(NULL, " ");
    }
    info ans_info = dfs(exp, 0, n);
    return ans_info.val;
}