[3] 단어 변환

#include <climits>
#include <iostream>
#include <string>
#include <vector>

using namespace std;

#define MAX 50

vector<string> vWord;
string targ = "";
bool vis[MAX + 1];
int ans = INT_MAX;

void DFS(string begin, int depth)
{
    if (targ == begin)
    {
        ans = min(ans, depth);
        return;
    }
    for (int i = 0; i < vWord.size(); i++)
    {
        int cnt = 0;

        for (int j = 0; j < vWord[i].size(); j++)
        {
            if (begin[j] != vWord[i][j])
                cnt++;

            if (cnt == 2)
                break;
        }
        if (cnt == 1)
        {
            // 백트래킹 수행
            if (!vis[i])
            {
                vis[i] = true;
                DFS(vWord[i], depth + 1);
                vis[i] = false;
            }
        }
    }
}

int solution(string begin, string target, vector<string> words)
{
    vWord.assign(words.begin(), words.end());
    targ = target;
    DFS(begin, 0);
    
    if(ans == INT_MAX)
        ans=0;
    
    return ans;
}