Update 37. Sudoku Solver.md

Author: TBXark

37. Sudoku Solver.md

@@ -191,7 +191,7 @@ class Solution {
 
 
 
-对权重遍历就行优化，提前得到每个空位有可能的值进行遍历，由于对集合进行遍历所以时间不稳定。最优时间可能在排名在100%
+对权重遍历就行优化，提前得到每个空位有可能的值进行遍历，由于对集合进行遍历顺序不确定，所以导致时间不稳定。最优时间可能在排名在100%
 ```
 Runtime: 36 ms, faster than 100.00% of Swift online submissions for Sudoku Solver.
 Memory Usage: 22.5 MB, less than 50.00% of Swift online submissions for Sudoku Solver.
@@ -206,12 +206,12 @@ class Solution {
         var clo = [Set<Character>].init(repeating: Set<Character>(), count: 9)
         var row = [Set<Character>].init(repeating: Set<Character>(), count: 9)
         var block = [Set<Character>].init(repeating: Set<Character>(), count: 9)
-        var points = [(p: (x: Int, y: Int), c: Set<Character>)]()
+        var points = [(p: (x: Int, y: Int), c: Int)]()
         for y in 0..<9 {
             for x in 0..<9 {
                 let c = board[y][x]
                 guard c != "." else {
-                    points.append((p: (x: x, y: y), c: Set<Character>()))
+                    points.append((p: (x: x, y: y), c: 0))
                     continue
                 }
                 clo[y].insert(c)
@@ -221,11 +221,10 @@ class Solution {
         }
         for i in 0..<points.count {
             let (x, y) = points[i].p
-            points[i].c = Solution.num.subtracting(clo[y].union(row[x]).union(block[x/3 + (y/3) * 3]))
+            points[i].c = clo[y].union(row[x]).union(block[x/3 + (y/3) * 3]).count
         }
-        points.sort(by: {  $0.c.count < $1.c.count  })
         _ = fillGrid(index: 0,
-                     point: points,
+                     point: points.sorted(by: {  $0.c > $1.c  }).map({ $0.p }),
                      board: &board,
                      clo: &clo,
                      row: &row,
@@ -234,17 +233,16 @@ class Solution {
 
 
     func fillGrid(index: Int,
-                  point: [(p: (x: Int, y: Int), c: Set<Character>)],
+                  point: [(x: Int, y: Int)],
                   board: inout [[Character]],
                   clo: inout [Set<Character>],
                   row: inout [Set<Character>],
                   block: inout [Set<Character>]) -> Bool {
         if index == point.count  {
             return true
         }
-        let (x, y) = point[index].p
-        
-        for c in point[index].c.subtracting(clo[y].union(row[x]).union(block[x/3 + (y/3) * 3])) {
+        let (x, y) = point[index]
+        for c in Solution.num.subtracting(clo[y].union(row[x]).union(block[x/3 + (y/3) * 3])) {
             board[y][x] = c
             clo[y].insert(c)
             row[x].insert(c)
@@ -261,4 +259,5 @@ class Solution {
         return false
     }
 }
+
 ```