8.18 [Leetcode] N-queens II

[Leetcode 52] N-queens II

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Question

Link

Follow up for n-queens problem.

Now, instead outputting board configurations and return the total number of distinct solutions.

Stats

Frequency	3
Difficulty	4
Adjusted difficulty	2
Time to use	——–

Ratings/color = 1 (white) 2 (lime) 3 (yellow) 4/5 (red)

Solution

I posted 2 solution by me. Second code is same as this guy ' s code.

My Code

Using global variable (similar to [Leetcode] n-queens)

1  Public classSolution {2     intres = 0;//Res should is global, cause Java func cannot return int value back.3      Public intTotalnqueens (intN) {4         //int res = 0;5         //int[] Col4row = new Int[n];6Helper (n, 0,New int[n]);7         returnRes;8     }9     Ten     Private voidHelperintNintRowint[] col4row) { One         if(row = = N) {//All positions is OK A++Res; -             return;//Don't forget to quit from this recursion. -         } the          for(inti = 0; I < n; i++) { -Col4row[row] = i;//put every col to this row to test the correctness. -             if(check (row, Col4row)) { -Helper (n, row+1, Col4row); +             } -         } +     } A      at     Private BooleanCheckintRowint[] col4row) { -          for(inti = 0; i < row; i++) { -             if(Col4row[i] = = Col4row[row] | | -Math.Abs (Col4row[i]-col4row[row]) = = row-i) -                 return false; -         } in         return true; -     } to}

Without using global variable,

 Public classSolution { Public intTotalnqueens (intN) {returnSolve (0, N,New int[n]); }    Private intSolveintRowintNint[] col4row) {        if(row = = N)return1; intAns = 0;  for(inti = 0; I < n; i++) {            BooleanConflict =false;  for(intj = 0; J < Row; J + +) //Check First, if not OK and go to next col, if ok let col4row[row] = i; if(i = = Col4row[j] | | row-j = = Math.Abs (i-Col4row[j])) Conflict=true; if(conflict)Continue; Col4row[row]=i; Ans+ = Solve (row + 1, N, Col4row);        //This row was finished, go to next row } returnans; }}

8.18 [Leetcode] N-queens II