Language: C++

#include <bits/stdc++.h>
#define rep(i,n) for(int i=0; i<n; i++)
#define PI 3.14159265359
#define INF 1000100100
#define all(x) (x).begin(),(x).end()
typedef long long ll;
using namespace std;
 
int main(){
    string s,t;  cin >> s >> t;
    int sll=s.length(); int tll=t.length();
    int dp[sll+1][sll+1];
    string dps[sll+1][sll+1];
    rep(i,sll+1){
        dp[i][0]=-1;
        dps[i][0]="";
    }
    rep(i,sll){
        dp[i][i+1]=INF;
        dps[i][i+1]="";
    }
    
    vector<vector<int> > al(26);
    rep(i,tll) al[t[i]-'a'].push_back(i);
 
    for(int i=1; i<sll+1; i++){
        for(int j=1; j<=i; j++){
            bool p=false;
            if(al[s[i-1]-'a'].empty()){
                dp[i][j]=dp[i-1][j];
                dps[i][j]=dps[i-1][j];
                continue;
            }
            int next=upper_bound(all(al[s[i-1]-'a']),dp[i-1][j-1]);
            if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
                if(*next<dp[i-1][j]){
                    dp[i][j]=*next;
                    dps[i][j]=dps[i-1][j-1]+s[i-1];
                    p=true;
                    break;
                }
            }
            if(p==false){
                dp[i][j]=dp[i-1][j];
                dps[i][j]=dps[i-1][j];
            }
        }
    }
 
    for(int i=sll; i>=0; i--){
        for(int j=sll; j>=i; j--){
            if(dp[j][i]!=INF){
              	cout << dps[j][i] << endl;
                return 0;
            }
        }
    }
    return 0;
}
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Compiler output:
a.cc: In function 'int main()':
a.cc:34:33: error: cannot convert '__gnu_cxx::__normal_iterator<int*, std::vector<int> >' to 'int' in initialization
   34 |             int next=upper_bound(all(al[s[i-1]-'a']),dp[i-1][j-1]);
      |                      ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                 |
      |                                 __gnu_cxx::__normal_iterator<int*, std::vector<int> >
a.cc:35:20: error: no match for 'operator!=' (operand types are 'int' and '__gnu_cxx::__normal_iterator<int*, std::vector<int> >')
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                |                           |
      |                int                         __gnu_cxx::__normal_iterator<int*, std::vector<int> >
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181,
                 from a.cc:1:
/usr/include/c++/14/bits/regex.h:1132:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1132 |     operator!=(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1132:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
/usr/include/c++/14/bits/regex.h:1212:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator!=(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1212 |     operator!=(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1212:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
/usr/include/c++/14/bits/regex.h:1305:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1305 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1305:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
/usr/include/c++/14/bits/regex.h:1379:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1379 |     operator!=(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1379:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   '__gnu_cxx::__normal_iterator<int*, std::vector<int> >' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
/usr/include/c++/14/bits/regex.h:1473:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1473 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1473:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
/usr/include/c++/14/bits/regex.h:1547:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1547 |     operator!=(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1547:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   '__gnu_cxx::__normal_iterator<int*, std::vector<int> >' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
/usr/include/c++/14/bits/regex.h:1647:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator!=(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1647 |     operator!=(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1647:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
/usr/include/c++/14/bits/regex.h:2213:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator!=(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)'
 2213 |     operator!=(const match_results<_Bi_iter, _Alloc>& __m1,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:2213:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'const std::__cxx11::match_results<_BiIter, _Alloc>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_pair.h:1052:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator!=(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1052 |     operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1052:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'const std::pair<_T1, _T2>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:455:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  455 |     operator!=(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:455:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
/usr/include/c++/14/bits/stl_iterator.h:500:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  500 |     operator!=(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:500:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
/usr/include/c++/14/bits/stl_iterator.h:1686:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator!=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1686 |     operator!=(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1686:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
/usr/include/c++/14/bits/stl_iterator.h:1753:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator!=(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1753 |     operator!=(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1753:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'int'
   35 |             if(next!=al[s[i-1]-'a'].begin()+al[s[i-1]-'a'].size()){
      |                                                                 ^
In file included from /usr/include/c++/14/bits/char_traits.h:42,
                 from /usr/include/c++/14/string:42,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/postypes.h:197:5: note: candidate: 'template<class _StateT> bool std::operator!=(const fpos<_StateT>&, const fpos<_StateT>&)'
  197 |     operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:197:5: note:   template argument deduction/substitution failed:
a.cc:35:65: note:   misma