Hello friends,
I was solving an array problem on leetcode using DFS but even after checking out my solution many times I am not able to find out what’s the problem with my solution.
Question- https://leetcode.com/problems/word-search/14
Solution link- https://ideone.com/foZ4sv9
I would be very thankful if someone helps me with this.
Apr '21Apr '21hi @simes I have removed all the compilation errors.
I have also find out the input for which answer is coming wrong which is mentioned in the ideone code.
I think the inrange function is causing some undefined behaviour but I am not able to find that.
Plz help.
#define inrange(i,j,n,m) (i>=0 && i<n && j>=0 && j<m)?true:false
What’s wrong with this? Remember it’s a macro, not a function call.
okay fine, but still did you find any problem with the code?
if(inrange(i+1,j,n,m) && board[i+1][j]==word[ind] && !visited[i+1][j])
When I was debugging I found that even for two different letters of board[i+1][j] and word[ind] the statements within the above written if conditional were getting executed.
A macro is simply a parameterised substitution. So this
if(inrange(i+1,j,n,m) && board[i+1][j]==word[ind] && !visited[i+1][j])
becomes this
if((i+1>=0 && i+1<n && j>=0 && j<m)?true:false && board[i+1][j]==word[ind] && !visited[i+1][j])
Is the problem more obvious now?
But what’s wrong with this if i and j have proper constraints then (i+1>=0 && i+1<n && j>=0 && j<m)?true:false will return true and then board[i+1][j]==word[ind] will be evaluated which will give false if letters are different and overall -> true and false will give false.
But still if statement is getting evaluated.
Am I interpreting it the wrong way?
I think it’s being interpreted like this:
if((i+1>=0 && i+1<n && j>=0 && j<m) ? (true) : (false && board[i+1][j]==word[ind] && !visited[i+1][j])))
so all it’s really checking is the array bounds, and not the word matches or visited. Which matches up with what I saw when testing it.
Test it. Replace
#define inrange(i,j,n,m) (i>=0 && i<n && j>=0 && j<m)?true:false
with
#define inrange(i,j,n,m) (i>=0 && i<n && j>=0 && j<m)
I got it @simes.
Thanks for your help 
