24 lines
716 B
Go
24 lines
716 B
Go
package q52
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func findNSolutions(nQueen, row int, rows, cols, diag1, diag2 []bool) int {
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solutions := 0
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if row == nQueen {
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return 1
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}
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for col := range nQueen {
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// if grid[row][col] is placeable
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if !rows[row] && !cols[col] && !diag1[row+col] && !diag2[row-col+nQueen] {
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rows[row], cols[col], diag1[row+col], diag2[row-col+nQueen] = true, true, true, true
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solutions += findNSolutions(nQueen, row+1, rows, cols, diag1, diag2)
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rows[row], cols[col], diag1[row+col], diag2[row-col+nQueen] = false, false, false, false
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}
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}
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return solutions
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}
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func totalNQueens(n int) int {
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buf := make([]bool, 6*n)
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return findNSolutions(n, 0, buf[0:n], buf[n:2*n], buf[2*n:4*n], buf[4*n:])
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}
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var _ = totalNQueens
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