Submission #2242861

---

Source Code Expand

#include <bits/stdc++.h>

using namespace std;

typedef long long lli;
typedef vector<lli> vll;
typedef vector<bool> vbl;
typedef vector<vector<lli>> mat;
typedef vector<unordered_map<lli,lli>> graph;

string a;

queue<vll> q;
set<lli> used;
mat mem;
string ans;

void output(){
  for(lli i = mem.size()-1;i >= 0;){
    ans.push_back((char)mem[i][0]);
    i = mem[i][1];
  }
  reverse(ans.begin(),ans.end());
  cout << ans << endl;
}


int main(){
  cin >> a;
  q.push(vll({-1,0,-1}));//point,char,prev;
  while(!q.empty()){
    lli point = q.front()[0];
    lli chr = q.front()[1];
    lli prev = q.front()[2];
    q.pop();
    if(used.count(point) != 0) continue;
    used.insert(point);
    mem.push_back(vll({chr,prev}));
    if(point == a.size()){
      output();
      return 0;
    }
    for(char c = 'a';c <= 'z';c++){
      lli p = find(a.begin()+point+1,a.end(),c)-a.begin();
      if(used.count(p) == 0) q.push(vll({p,(lli)c,(lli)mem.size()-1ll}));
    }
  }

}

Submission Info

Judge Result