determine 9 x 9 Sudoku board valid only fill cell need validate accord follow ruleseach row contain digit 19 repetitioneach column contain digit 19 repetitioneach 3 x 3 subboxes grid contain digit 19 repetitionnotea Sudoku board partially fill valid necessarily solvableonly fill cell need validate accord mention rule Example 1input board 537619598686348317266284195879output trueExample 2input board 837619598686348317266284195879output falseExplanation Same Example 1 5 leave corner modify 8 since 8 leave 3x3 subbox invalid Constraintsboardlength 9boardilength 9boardij digit 19