Changes

__global__ void superSolve(int * d_a) { //Used to remember which row | col | box ( section ) have which values __shared__ bool rowHas[N][N]; __shared__ bool colHas[N][N]; __shared__ bool boxHas[N][N]; //Used to ensure that the table has changed __shared__ int added, past; //Number of spaces which can place the number in each section __shared__ int rowCount[N][N]; __shared__ int colCount[N][N]; __shared__ int boxCount[N][N]; //Use registry memory to remember what values were seen bool notSeen[N]; //Where the square is located in the Sudoku int row = threadIdx.x; int col = threadIdx.y; int box = row / BOXWIDTH + (col / BOXWIDTH) * BOXWIDTH; //Unique identifier for each square in row, col, box //Corresponds to the generic Sudoku Solve //Using a Sudoku to solve a Sudoku !!! int offset = col + (row % BOXWIDTH) * BOXWIDTH + (box % BOXWIDTH); //Square's location in the Sudoku int gridIdx = col * N + row; int at = d_a[gridIdx];

if (gridIdx == 0)//Used to remember which row | col | box ( section ) have which Thread at 0,0 sets values __shared__ bool rowHas[N][N]; __shared__ bool colHas[N][N]; __shared__ bool boxHas[N][N] added = -1;

//Used to ensure that the table has changed rowHas[row][col] = false; __shared__ int added, past colHas[row][col] = false; boxHas[row][col] = false;

for (int i = 0; i < N; i++) notSeen[i] = true; __syncthreads(); if (at != UNASSIGNED) { rowHas[row][at - 1] = true; colHas[col][at - 1] = true; boxHas[box][at - 1] = true; } do { //RESET counters rowCount[row][col] = 0; colCount[row][col] = 0; boxCount[row][col] = 0; __syncthreads(); if (gridIdx == 0) //Number forget previous change past = added; int count = 0; //number of spaces values which can place the fit in this square int guess = at; //last value found which can fit in this square for (int idx = 0; idx < N; ++idx) { //Ensures that every square in each section is working on a different number in each the section __shared__ int num = (idx + offset) % N; if (at == UNASSIGNED && notSeen[num]){ if (rowHas[row][num] || boxHas[box][num] || colHas[col][num]) { notSeen[num] = false; } else { count++; guess = num + 1; rowCount[Nrow][Nnum]++; __shared__ int colCount[Ncol][Nnum]++; __shared__ int boxCount[Nbox][Nnum]++; } } __syncthreads(); } //Use registry memory to remember what Find values were seenwhich can go in only one spot in the section if (count > 1) { for (int idx = 0; idx < N; ++idx) { bool if (notSeen[Nidx] && ( rowCount[row][idx] == 1 || boxCount[box][idx] || colCount[col][idx]== 1)) { count = 1; guess = idx + 1; } } } //Where the square is located in the SudokuOne value Must go here if (count == 1) { at = guess--; int rowHas[row ][guess] = threadIdx.xtrue; int colHas[col ][guess] = threadIdx.ytrue; int boxHas[box ][guess] = row / BOXWIDTH + true; added = gridIdx; } __syncthreads(col / BOXWIDTH) * BOXWIDTH;

//Unique identifier for each square in row, col, box //Corresponds to the generic Sudoku Solve //Using a Sudoku to solve a Sudoku !!! int offset = col + (row % BOXWIDTH) * BOXWIDTH + (box % BOXWIDTH);  //Square's location in the Sudoku int gridIdx = col * N + row;  int at = d_a[gridIdx];  if (gridIdx == 0)//Thread at 0,0 sets values added = -1;  rowHas[row][col] = false; colHas[row][col] = false; boxHas[row][col] = false;  for (int i = 0; i < N; i++) notSeen[i] = true;  __syncthreads();  if (at != UNASSIGNED) { rowHas[row][at - 1] = true; colHas[col][at - 1] = true; boxHas[box][at - 1] = true; }  //Previous loop has not changed any values do { //RESET counters rowCount[row][col] = 0; colCount[row][col] = 0; boxCount[row][col] = 0; __syncthreads();  if (gridIdx == 0) //forget previous change past = added; int count = 0; //number of values which can fit in this square int guess = at; //last value found which can fit in this square for (int idx = 0; idx < N; ++idx) { //Ensures that every square in each section is working on a different number in the section int num = (idx + offset) % N; if (at == UNASSIGNED && notSeen[num]){ if (rowHas[row][num] || boxHas[box][num] || colHas[col][num]) { notSeen[num] = false; } else { count++; guess = num + 1; rowCount[row][num] ++; colCount[col][num] ++; boxCount[box][num] ++; } } __syncthreads(); } //Find values which can go in only one spot in the section if (count > 1) { for (int idx = 0; idx < N; ++idx) { if (notSeen[idx] && ( rowCount[row][idx] == 1 || boxCount[box][idx] || colCount[col][idx] == 1)) { //In this section this value can only appear in this square count = 1; guess = idx + 1; } } } //One value Must go here if (count == 1) { at = guess--; rowHas[row][guess] = true; colHas[col][guess] = true; boxHas[box][guess] = true; added = gridIdx; } __syncthreads(); } while (added != past); d_a[gridIdx] = at; }