Language: C++

#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define eb emplace_back
#define mt make_tuple
#define all(x) (x).begin(), (x).end() 
#define MOD 1000000007

typedef long long ll;
typedef pair <int, int> ii;
typedef pair <ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef long double ld;
typedef pair<int,ii>iii;

const ll INF=LLONG_MAX;
int h,w,k;
int x1,x2,y1,y2;
const int dx[]={0,-1,0,1};
const int dy[]={-1,0,1,0};

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    //freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
	cin >> h >> w >> k;
	cin >> x1 >> y1 >> x2 >> y2;
	x1--; y1--; x2--; y2--;
	char grid[h][w];
	int vis[h][w],ans[h][w];
	memset(vis,-1,sizeof(vis));
	memset(ans,-1,sizeof(ans));
	for(int i=0; i<h; i++)
		for(int j=0; j<w; j++)
			cin >> grid[i][j];
	priority_queue<pair<int,iii>,vector<pair<int,iii>>,greater<pair<int,iii>>>pq; //dist,pos
	pq.push({0,{0,{x1,y1}}});
	while(!pq.empty()){
		int dist = pq.top().fi;
		int cnt = pq.top().se.fi;
		int x=pq.top().se.se.fi;
		int y=pq.top().se.se.se;
		//cout << x << ' ' << y << ' ' << cnt << ' ' << dist << endl;
		pq.pop();
		if(ans[x][y]!=-1&&cnt>ans[x][y])continue;
		vis[x][y]=dist;
		ans[x][y]=cnt;
		if(x==x2&&y==y2)break;
		for(int i=0; i<4; i++){
			int X=x;
			int Y=y;
			for(int j=0; j<k; j++){
				X+=dx[i]; Y+=dy[i];
				if(X<0||X>=h)break;
				if(Y<0||Y>=w)break;
				if(grid[X][Y]=='@')break;
				if(ans[X][Y]!=-1&&cnt+1>ans[X][Y])continue;
				if(j==0||j==k-1)pq.push({dist+j,{cnt+1,{X,Y}}});
			}
		}
	}
	cout << ans[x2][y2] << endl;
}
	
// READ & UNDERSTAND
// ll, int overflow, array bounds, memset(0)
// special cases (n=1?), n+1 (1-index)
// do smth instead of nothing & stay organized
// WRITE STUFF DOWN


Compiler output:
a.cc:22:11: error: 'int y1' redeclared as different kind of entity
   22 | int x1,x2,y1,y2;
      |           ^~
In file included from /usr/include/features.h:523,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/os_defines.h:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/c++config.h:683,
                 from /usr/include/c++/14/cassert:43,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:33,
                 from a.cc:1:
/usr/include/x86_64-linux-gnu/bits/mathcalls.h:257:1: note: previous declaration 'double y1(double)'
  257 | __MATHCALL (y1,, (_Mdouble_));
      | ^~~~~~~~~~
a.cc: In function 'int main()':
a.cc:31:19: error: no match for 'operator>>' (operand types are 'std::basic_istream<char>::__istream_type' {aka 'std::basic_istream<char>'} and 'double(double) noexcept')
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |         ~~~~~~~~~ ^~ ~~
      |             |        |
      |             |        double(double) noexcept
      |             std::basic_istream<char>::__istream_type {aka std::basic_istream<char>}
In file included from /usr/include/c++/14/sstream:40,
                 from /usr/include/c++/14/complex:45,
                 from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127:
/usr/include/c++/14/istream:170:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  170 |       operator>>(bool& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:170:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: cannot bind non-const lvalue reference of type 'bool&' to a value of type 'double (*)(double) noexcept'
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
/usr/include/c++/14/istream:174:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  174 |       operator>>(short& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:174:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: invalid conversion from 'double (*)(double) noexcept' to 'short int' [-fpermissive]
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
      |                      |
      |                      double (*)(double) noexcept
a.cc:31:22: error: cannot bind rvalue '(short int)y1' to 'short int&'
/usr/include/c++/14/istream:177:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  177 |       operator>>(unsigned short& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:177:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: invalid conversion from 'double (*)(double) noexcept' to 'short unsigned int' [-fpermissive]
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
      |                      |
      |                      double (*)(double) noexcept
a.cc:31:22: error: cannot bind rvalue '(short unsigned int)y1' to 'short unsigned int&'
/usr/include/c++/14/istream:181:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  181 |       operator>>(int& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:181:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: invalid conversion from 'double (*)(double) noexcept' to 'int' [-fpermissive]
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
      |                      |
      |                      double (*)(double) noexcept
a.cc:31:22: error: cannot bind rvalue '(int)y1' to 'int&'
/usr/include/c++/14/istream:184:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  184 |       operator>>(unsigned int& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:184:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: invalid conversion from 'double (*)(double) noexcept' to 'unsigned int' [-fpermissive]
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
      |                      |
      |                      double (*)(double) noexcept
a.cc:31:22: error: cannot bind rvalue '(unsigned int)y1' to 'unsigned int&'
/usr/include/c++/14/istream:188:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  188 |       operator>>(long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:188:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: invalid conversion from 'double (*)(double) noexcept' to 'long int' [-fpermissive]
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
      |                      |
      |                      double (*)(double) noexcept
a.cc:31:22: error: cannot bind rvalue '(long int)y1' to 'long int&'
/usr/include/c++/14/istream:192:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  192 |       operator>>(unsigned long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:192:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: invalid conversion from 'double (*)(double) noexcept' to 'long unsigned int' [-fpermissive]
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
      |                      |
      |                      double (*)(double) noexcept
a.cc:31:22: error: cannot bind rvalue '(long unsigned int)y1' to 'long unsigned int&'
/usr/include/c++/14/istream:199:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  199 |       operator>>(long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:199:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: invalid conversion from 'double (*)(double) noexcept' to 'long long int' [-fpermissive]
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
      |                      |
      |                      double (*)(double) noexcept
a.cc:31:22: error: cannot bind rvalue '(long long int)y1' to 'long long int&'
/usr/include/c++/14/istream:203:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  203 |       operator>>(unsigned long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:203:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: invalid conversion from 'double (*)(double) noexcept' to 'long long unsigned int' [-fpermissive]
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
      |                      |
      |                      double (*)(double) noexcept
a.cc:31:22: error: cannot bind rvalue '(long long unsigned int)y1' to 'long long unsigned int&'
/usr/include/c++/14/istream:328:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(void*&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  328 |       operator>>(void*& __p)
      |       ^~~~~~~~
/usr/include/c++/14/istream:328:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: invalid conversion from 'double (*)(double) noexcept' to 'void*' [-fpermissive]
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
      |                      |
      |                      double (*)(double) noexcept
a.cc:31:22: error: cannot bind rvalue '(void*)y1' to 'void*&'
/usr/include/c++/14/istream:122:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__istream_type& (*)(__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  122 |       operator>>(__istream_type& (*__pf)(__istream_type&))
      |       ^~~~~~~~
/usr/include/c++/14/istream:122:7: note:   conversion of argument 1 would be ill-formed:
a.cc:31:22: error: invalid conversion from 'double (*)(double) noexcept' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&)' {aka 'std::basic_istream<char>& (*)(std::basic_istream<char>&)'} [-fpermissive]
   31 |         cin >> x1 >> y1 >> x2 >> y2;
      |                      ^~
      |                      |
      |                      double (*)(double) noexcept
/usr/include/c++/14/istream:126:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__ios_type& (*)(__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>; __ios_type = std::basic_ios<char>]' (near match)
  126 |       operator>>(__ios_type& (*__pf)(__ios_type&))
      |       ^~~~~~~~
/usr/include/c++/14/istream:126:7: note:   conversion of a