Language: C++

#include <bits/stdc++.h>
 
#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)
 
#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=(int)(a)-1;i>=(int)(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)
 
#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
 
// #define DEBUG
 
#ifdef DEBUG
    #define dump(...) fprintf(stderr, __VA_ARGS__)
#else
    #define dump(...)
#endif
 
template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}
 
using namespace std;
using ll=long long;
using vi=vector<int>;
using vll=vector<ll>;
 
const double EPS = 1e-10;
const double PI = acos(-1.0);
const ll inf =1LL << 62;
const ll mod=1000000007LL;
const int dx[4]={1,0,-1,0};
const int dy[4]={0,1,0,-1};
 
 
ll extgcd(ll a,ll b,ll& x,ll& y){x=1,y=0;ll g=a;if(b!=0) g=extgcd(b,a%b,y,x),y-=a/b*x;return g;}
ll ADD(const ll &a, const ll &b,const ll &mod) { return (a+b)%mod;}
ll SUB(const ll &a, const ll &b,const ll &mod) { return (a-b+mod)%mod;}
ll MUL(const ll &a, const ll &b,const ll &mod) { return (1LL*a*b)%mod;}
ll DIV(const ll &a, const ll &b,const ll &mod) {ll x,y; extgcd(b,mod,x,y);return MUL(a,(x+mod)%mod,mod);}
 
random_device rd;
mt19937 mt(rd());
uniform_int_distribution<int> dice(1,6);
uniform_real_distribution<double> score(0.0,10.0);

const int N = 1e6;
vi graph[N];

using ResElem = tuple<string, string>;
set<ResElem> s;

inline void add_edge(int a, int b){
    graph[a].emplace_back(b);
    graph[b].emplace_back(a);
}

int d, n;
map<string, int> s2i;
map<int, string> i2s;

void dfs(int sv, int v, int depth){
    if(depth > d) return;
    if(sv != v and v < n){
        string a = i2s[v], b = i2s[sv];
        if(a > b) swap(a, b);
        s.insert(ResElem(a, b));
    }

    for(auto& nv : graph[v]){
        dfs(sv, nv, depth + 1);
    }
}

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

    for(; cin >> n >> d, n;){
        vector<string> names(n);
        for(auto& e : names) cin >> e;

        s2i.clear();
        i2s.clear();
        int idx = 0;
        auto add_vertex = [&](string& name){
            if(s2i.find(name) == end(s2i)){
                s2i[name] = idx; i2s[idx] = name; idx++;
            }
            return s2i[name];
        };
        for(auto& e : names) add_vertex(e);

        rep(i, N) graph[i].clear();
        for(auto& cur : names){
            string next;
            int len = cur.size();
            int v = s2i[cur];

            // delete
            rep(i, len){
                next = cur.substr(0, i) + cur.substr(i + 1);
                int nv = add_vertex(next);
                add_edge(v, nv);
            }

            // insert
            rep(i, len + 1){
                rep(j, 'z' - 'a' + 1){
                    char c = (char)('a' + j);
                    next = cur.substr(0, i) + c + cur.substr(i);
                    int nv = add_vertex(next);
                    add_edge(v, nv);
                }
            }

            // replace
            rep(i, len){
                rep(j, 'z' - 'a' + 1){
                    char c = (char)('a' + j);
                    next = cur.substr(0, i) + c;
                    if(i + 1 < len) next += cur.substr(i + 1);
                    int nv = add_vertex(next);
                    add_edge(v, nv);
                }
            }

            // swap
            rep(i, len - 1){
                next = cur;
                swap(next[i], next[i + 1]);
                int nv = add_vertex(next);
                add_edge(v, nv);
            }
        }

        s.clear();
        rep(i, n){
            dfs(i, i, 0);
        }

        for(auto& e : s){
            int a, b; tie(a, b) = e;
            cout << i2s[a] << "," << i2s[b] << endl;
        }
        cout << s.size() << endl;
    }

    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:149:35: error: no match for 'operator=' (operand types are 'std::tuple<int&, int&>' and 'const std::tuple<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >')
  149 |             int a, b; tie(a, b) = e;
      |                                   ^
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/string:68,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:1:
/usr/include/c++/14/tuple:2355:9: note: candidate: 'template<class _U1, class _U2> std::__enable_if_t<((bool)__assignable<const _U1&, const _U2&>()), std::tuple<_T1, _T2>&> std::tuple<_T1, _T2>::operator=(const std::tuple<_U1, _U2>&) [with _U2 = _U1; _T1 = int&; _T2 = int&]'
 2355 |         operator=(const tuple<_U1, _U2>& __in)
      |         ^~~~~~~~
/usr/include/c++/14/tuple:2355:9: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/14/bits/stl_pair.h:60,
                 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/type_traits: In substitution of 'template<bool _Cond, class _Tp> using std::__enable_if_t = typename std::enable_if::type [with bool _Cond = false; _Tp = std::tuple<int&, int&>&]':
/usr/include/c++/14/tuple:2355:2:   required by substitution of 'template<class _U1, class _U2> std::__enable_if_t<((bool)__assignable<const _U1&, const _U2&>()), std::tuple<int&, int&>&> std::tuple<int&, int&>::operator=(const std::tuple<_T1, _T2>&) [with _U1 = std::__cxx11::basic_string<char>; _U2 = std::__cxx11::basic_string<char>]'
a.cc:149:35:   required from here
  149 |             int a, b; tie(a, b) = e;
      |                                   ^
/usr/include/c++/14/type_traits:138:11: error: no type named 'type' in 'struct std::enable_if<false, std::tuple<int&, int&>&>'
  138 |     using __enable_if_t = typename enable_if<_Cond, _Tp>::type;
      |           ^~~~~~~~~~~~~
/usr/include/c++/14/tuple:2365:9: note: candidate: 'template<class _U1, class _U2> std::__enable_if_t<((bool)__assignable<_U1, _U2>()), std::tuple<_T1, _T2>&> std::tuple<_T1, _T2>::operator=(std::tuple<_U1, _U2>&&) [with _U2 = _U1; _T1 = int&; _T2 = int&]'
 2365 |         operator=(tuple<_U1, _U2>&& __in)
      |         ^~~~~~~~
/usr/include/c++/14/tuple:2365:9: note:   template argument deduction/substitution failed:
a.cc:149:35: note:   types 'std::tuple<_T1, _T2>' and 'const std::tuple<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >' have incompatible cv-qualifiers
  149 |             int a, b; tie(a, b) = e;
      |                                   ^
/usr/include/c++/14/tuple:2375:9: note: candidate: 'template<class _U1, class _U2> std::__enable_if_t<((bool)__assignable<const _U1&, const _U2&>()), std::tuple<_T1, _T2>&> std::tuple<_T1, _T2>::operator=(const std::pair<_U1, _U2>&) [with _U2 = _U1; _T1 = int&; _T2 = int&]'
 2375 |         operator=(const pair<_U1, _U2>& __in)
      |         ^~~~~~~~
/usr/include/c++/14/tuple:2375:9: note:   template argument deduction/substitution failed:
a.cc:149:35: note:   'const std::tuple<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >' is not derived from 'const std::pair<_T1, _T2>'
  149 |             int a, b; tie(a, b) = e;
      |                                   ^
/usr/include/c++/14/tuple:2386:9: note: candidate: 'template<class _U1, class _U2> std::__enable_if_t<((bool)__assignable<_U1, _U2>()), std::tuple<_T1, _T2>&> std::tuple<_T1, _T2>::operator=(std::pair<_U1, _U2>&&) [with _U2 = _U1; _T1 = int&; _T2 = int&]'
 2386 |         operator=(pair<_U1, _U2>&& __in)
      |         ^~~~~~~~
/usr/include/c++/14/tuple:2386:9: note:   template argument deduction/substitution failed:
a.cc:149:35: note:   types 'std::pair<_T1, _T2>' and 'const std::tuple<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >' have incompatible cv-qualifiers
  149 |             int a, b; tie(a, b) = e;
      |                                   ^
/usr/include/c++/14/tuple:2332:7: note: candidate: 'std::tuple<_T1, _T2>& std::tuple<_T1, _T2>::operator=(std::__conditional_t<((bool)__assignable<const _T1&, const _T2&>()), const std::tuple<_T1, _T2>&, const std::__nonesuch&>) [with _T1 = int&; _T2 = int&; std::__conditional_t<((bool)__assignable<const _T1&, const _T2&>()), const std::tuple<_T1, _T2>&, const std::__nonesuch&> = const std::tuple<int&, int&>&]'
 2332 |       operator=(__conditional_t<__assignable<const _T1&, const _T2&>(),
      |       ^~~~~~~~
/usr/include/c++/14/tuple:2334:52: note:   no known conversion for argument 1 from 'const std::tuple<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >' to 'std::__conditional_t<true, const std::tuple<int&, int&>&, const std::__nonesuch&>' {aka 'const std::tuple<int&, int&>&'}
 2332 |       operator=(__conditional_t<__assignable<const _T1&, const _T2&>(),
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 2333 |                                 const tuple&,
      |                                 ~~~~~~~~~~~~~       
 2334 |                                 const __nonesuch&> __in)
      |                                 ~~~~~~~~~~~~~~~~~~~^~~~
/usr/include/c++/14/tuple:2343:7: note: candidate: 'std::tuple<_T1, _T2>& std::tuple<_T1, _T2>::operator=(std::__conditional_t<((bool)__assignable<_T1, _T2>()), std::tuple<_T1, _T2>&&, std::__nonesuch&&>) [with _T1 = int&; _T2 = int&; std::__conditional_t<((bool)__assignable<_T1, _T2>()), std::tuple<_T1, _T2>&&, std::__nonesuch&&> = std::tuple<int&, int&>&&]'
 2343 |       operator=(__conditional_t<__assignable<_T1, _T2>(),
      |       ^~~~~~~~
/usr/include/c++/14/tuple:2345:47: note:   no known conversion for argument 1 from 'const std::tuple<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >' to 'std::__conditional_t<true, std::tuple<int&, int&>&&, std::__nonesuch&&>' {aka 'std::tuple<int&, int&>&&'}
 2343 |       operator=(__conditional_t<__assignable<_T1, _T2>(),
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 2344 |                                 tuple&&,
      |                                 ~~~~~~~~       
 2345 |                                 __nonesuch&&> __in)
      |                                 ~~~~~~~~~~~~~~^~~~