feat(#36): solve the problem #36.Valid Sudoku

Author: geemo

36.Valid Sudoku/README.md

@@ -0,0 +1,73 @@
+Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:
+
+- Each row must contain the digits 1-9 without repetition.
+- Each column must contain the digits 1-9 without repetition.
+- Each of the 9 3x3 sub-boxes of the grid must contain the digits 1-9 without repetition.
+
+A partially filled sudoku which is valid.
+
+The Sudoku board could be partially filled, where empty cells are filled with the character '.'.
+
+**Example 1:**
+```
+Input:
+[
+  ["5","3",".",".","7",".",".",".","."],
+  ["6",".",".","1","9","5",".",".","."],
+  [".","9","8",".",".",".",".","6","."],
+  ["8",".",".",".","6",".",".",".","3"],
+  ["4",".",".","8",".","3",".",".","1"],
+  ["7",".",".",".","2",".",".",".","6"],
+  [".","6",".",".",".",".","2","8","."],
+  [".",".",".","4","1","9",".",".","5"],
+  [".",".",".",".","8",".",".","7","9"]
+]
+Output: true
+```
+**Example 2:**
+```
+Input:
+[
+  ["8","3",".",".","7",".",".",".","."],
+  ["6",".",".","1","9","5",".",".","."],
+  [".","9","8",".",".",".",".","6","."],
+  ["8",".",".",".","6",".",".",".","3"],
+  ["4",".",".","8",".","3",".",".","1"],
+  ["7",".",".",".","2",".",".",".","6"],
+  [".","6",".",".",".",".","2","8","."],
+  [".",".",".","4","1","9",".",".","5"],
+  [".",".",".",".","8",".",".","7","9"]
+]
+Output: false
+Explanation: Same as Example 1, except with the 5 in the top left corner being 
+    modified to 8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.
+```
+**Note:**
+
+- A Sudoku board (partially filled) could be valid but is not necessarily solvable.
+- Only the filled cells need to be validated according to the mentioned rules.
+- The given board contain only digits 1-9 and the character '.'.
+- The given board size is always 9x9.
+
+**Solution:**
+
+```golang
+import "fmt"
+func isValidSudoku(board [][]byte) bool {
+  m := make(map[string]bool)
+  for i := 0; i < 9; i++ {
+    for j := 0; j < 9; j++ {
+      if board[i][j] != '.' {
+        tag := fmt.Sprintf("(%c)", board[i][j])
+        r, c, rc := fmt.Sprintf("%d%s", i, tag), fmt.Sprintf("%s%d", tag, j), fmt.Sprintf("%d%s%d", i / 3, tag, j / 3)
+        if m[r] || m[c] || m[rc] {
+          return false
+        }
+        m[r], m[c], m[rc] = true, true, true
+      }
+    }
+  }
+
+  return true
+}
+```