Sudoku: Difference between revisions

=={{header|D}}==

<lang d>

import std.stdio;

bool[char]genFull() {

return ['1':true,

'2':true,

'3':true,

'4':true,

'5':true,

'6':true,

'7':true,

'8':true,

'9':true];

}

// these three functions assume that the number has not already been found

bool[char]availRow(int x,int y,bool[char]available=genFull()) {

// x designates row, y designates column

foreach(ele;puzzle[x]) {

if (ele != '_') available.remove(ele);

}

return available;

}

bool[char]availCol(int x,int y,bool[char]available=genFull()) {

// x designates row, y designates column

for(int i = 0;i<9;i++) {

if (puzzle[i][y] != '_') available.remove(puzzle[i][y]);

}

return available;

}

bool[char]availBox(int x,int y,bool[char]available=genFull()) {

// x designates row, y designates column

// get a base index for the boxes

int bx = x/3;bx*=3;

int by = y/3;by*=3;

for(int i = 0;i<3;i++) for(int j = 0;j<3;j++) {

if (puzzle[bx+i][by+j] != '_') available.remove(puzzle[bx+i][by+j]);

}

return available;

}

char[][]puzzle;

void main() {

puzzle ~= "394__267_".dup;

puzzle ~= "___3__4__".dup;

puzzle ~= "5__69__2_".dup;

puzzle ~= "_45___9__".dup;

puzzle ~= "6_______7".dup;

puzzle ~= "__7___58_".dup;

puzzle ~= "_1__67__8".dup;

puzzle ~= "__9__8___".dup;

puzzle ~= "_264__735".dup;

while(1) {

bool done = true;

foreach(i,row;puzzle) foreach(j,ref ele;row) if (ele == '_') {

// poke at the elements that are _

auto remaining = availBox(i,j,availRow(i,j,availCol(i,j)));

if (remaining.keys.length == 1) ele = remaining.keys[0];

else done = false;

}

if (done) break;

}

// write out completed puzzle

writefln("Completed puzzle:");

foreach(row;puzzle) writefln("%s",row);

}

</lang>