Improve 0036-valid-sudoku.go

go/0036-valid-sudoku.go

@@ -1,34 +1,25 @@
-// Time Complexity O(n2)
 func isValidSudoku(board [][]byte) bool {
-
-    hashMap := make(map[string]bool)
-
-    for i:=0; i<9; i ++ {
-        for j:=0;j<9; j++ {
-
-            row:= i
-            column :=j
-
-            current_val :=string(board[i][j])
+	rows := [9][9]bool{}
+	cols := [9][9]bool{}
+	squares := [9][9]bool{}
 
-            if current_val =="." { 
-                continue
-            }
-            _,ok1 := hashMap[current_val + "found in row" + string(row)]
-            _,ok2 := hashMap[current_val + "found in column"+  string(column)]
-            _,ok3 := hashMap[current_val + "found in grid" + string(i/3) + "-" + string(j/3)]            
-
-            if ok1 ||ok2||ok3{
-
-                return false
-            } else {
-                hashMap[current_val + "found in row" + string(row)] = true
-                hashMap[current_val + "found in column"+  string(column)] = true
-                hashMap[current_val + "found in grid" + string(i/3) + "-" + string(j/3)]= true                
-            }
-        }
+	for r := range 9 {
+		for c := range 9 {
+			if board[r][c] == '.' {
+				continue
+			}
 
-    }
-    return true    
-
+			value := board[r][c] - '1'
+			s := r/3*3 + c/3
+			if rows[r][value] || cols[c][value] || squares[s][value] {
+				return false
+			}
+
+			rows[r][value] = true
+			cols[c][value] = true
+			squares[s][value] = true
+		}
+	}
+
+	return true
 }