Compiler 2012

This is an old revision of the document!

---

/* The eight queens solver */
 
int main(string[] args) {
  int N;
  int[] row, col;
  int[][] d;
 
  N = 8;
  row = new int[N];
  col = new int[N];
  d = new int[][2];
  d[0] = new int[N+N-1];
  d[1] = new int[N+N-1];
 
  fill(row, 0);
  fill(col, 0);
  fill(d[0], 0);
  fill(d[1], 0);
 
  try(N, row, col, d, 0);
 
  return 0;
}
 
int fill(int[] a, int v) {
  int i;
 
  for (i = 0; i < a.length; i = i+1) {
    a[i] = v;
  }
  return 0;
}
 
int printBoard(int[] col) {
  int i, j;
 
  for (i = 0; i < col.length; i = i+1) {
    for (j = 0; j < col.length; j = j+1) {
      if (col[i] == j) {
        printString(" O");
      } else {
        printString(" .");
      }
    }
    printLine("");
  }
  printLine("");
  return 0;
}
 
int try(int N, int[] row, int[] col, int[][] d, int c) {
  int r;
 
  if (c == N) {
    printBoard(col);
  } else {
    for (r = 0; r < N; r = r+1) {
      if (row[r] == 0 && d[0][r+c] == 0 && d[1][r+N-1-c] == 0) {
        row[r] = d[0][r+c] = d[1][r+N-1-c] = 1;
        col[c] = r;
        try(N, row, col, d, c+1);
        row[r] = d[0][r+c] = d[1][r+N-1-c] = 0;
      }
    }
  }
  return 0;
}