Submission #6535492

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
using ll = long long;

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl

const ll mod = 1e9 + 7;
const ll inf = 1e18;

ll dist(string s, string t){
    ll L = s.size();
    ll ret = s.size();
    FOR(i, 0, L){
        if(s[i]==t[i]) ret--;
    }
    return ret;
}

vector<vector<ll>> G;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    string first, last;
    cin >> first >> last;

    if(first==last){
        p(0);
        p(first);
        p(last);
        return 0;
    }

    ll N; cin >> N;
    vector<string> W;
    W.push_back(first);
    FOR(i, 0, N){
        string word; cin >> word;
        W.push_back(word);
    }
    W.push_back(last);
    N+=2;
    G.resize(N);

    vector<ll> d(1005, inf);

    FOR(i, 0, N){
        FOR(j, i+1, N){
            if(dist(W[i], W[j])==1){
                // edge
                G[i].push_back(j);
                G[j].push_back(i);
            }
        }
    }

    // bfs
    queue<ll> que;
    que.push(0);
    d[0]=0;
    while(!que.empty()){
        ll i = que.front();
        que.pop();
        for(ll to : G[i]){
            if(d[to]==inf){
                d[to] = d[i]+1;
                que.push(to);
            }
        }
    }
    if(d[N-1]==inf){
        p(-1);
        return 0;
    }

    // N-1から逆向きにたどる
    vector<string> Ans;
    Ans.push_back(last);
    ll current = N-1;
    ll D = d[N-1];
    while(D>0){
        for(ll to : G[current]){
            if(d[to]==D-1){
                // そこにいく
                Ans.push_back(W[to]);
                D--;
                current = to;
                break;
            }
        }
    }
    reverse(ALL(Ans));
    p(Ans.size()-2);
    for(string w : Ans){
        p(w);
    }
    
    return 0;
}

Submission Info

Judge Result