wordle.cpp

#ifndef RECCHECK
#include <iostream>
#include <map>
#include <set>
#include <string>
#endif

#include "wordle.h"
#include "dict-eng.h"
using namespace std;

static void erase_one_char(string& s, char c)
{
    for(size_t i = 0; i < s.size(); ++i){
        if(s[i] == c){
            s.erase(i, 1);
            return;
        }
    }
}

static void solve(const string& in,
                  const set<string>& dict,
                  string& cur,
                  int idx,
                  string floating_left,
                  set<string>& results)
{
    int n = (int)in.size();

    if(idx == n){
        if(floating_left.empty() && dict.find(cur) != dict.end()){
            results.insert(cur);
        }
        return;
    }

    int remaining = n - idx;
    if((int)floating_left.size() > remaining){
        return;
    }

    if(in[idx] != '-'){
        cur[idx] = in[idx];
        erase_one_char(floating_left, in[idx]);
        solve(in, dict, cur, idx + 1, floating_left, results);
    }
    else{
        for(char c = 'a'; c <= 'z'; ++c){
            cur[idx] = c;
            string nextFloating = floating_left;
            erase_one_char(nextFloating, c);
            int nextRemaining = remaining - 1;
            if((int)nextFloating.size() > nextRemaining){
                continue;
            }
            solve(in, dict, cur, idx + 1, nextFloating, results);
        }
    }
}

set<string> wordle(
    const string& in,
    const string& floating,
    const set<string>& dict)
{
    set<string> results;
    string cur = in;
    solve(in, dict, cur, 0, floating, results);
    return results;
}