959 wrong answer

Author: aQuaYi

Algorithms/0959.regions-cut-by-slashes/1.png

@@ -0,0 +1,85 @@
+# [959. Regions Cut By Slashes](https://leetcode.com/problems/regions-cut-by-slashes/)
+
+In a N x N grid composed of 1 x 1 squares, each 1 x 1 square consists of a /, \, or blank space.  These characters divide the square into contiguous regions.
+
+(Note that backslash characters are escaped, so a \ is represented as "\\".)
+
+Return the number of regions.
+
+Example 1:
+
+```text
+Input:
+[
+  " /",
+  "/ "
+]
+
+Output: 2
+Explanation: The 2x2 grid is as follows:
+```
+
+![1](1.png)
+
+Example 2:
+
+```text
+Input:
+[
+  " /",
+  "  "
+]
+Output: 1
+Explanation: The 2x2 grid is as follows:
+```
+
+![2](2.png)
+
+Example 3:
+
+```text
+Input:
+[
+  "\\/",
+  "/\\"
+]
+Output: 4
+Explanation: (Recall that because \ characters are escaped, "\\/" refers to \/, and "/\\" refers to /\.)
+The 2x2 grid is as follows:
+```
+
+![3](3.png)
+
+Example 4:
+
+```text
+Input:
+[
+  "/\\",
+  "\\/"
+]
+Output: 5
+Explanation: (Recall that because \ characters are escaped, "/\\" refers to /\, and "\\/" refers to \/.)
+The 2x2 grid is as follows:
+```
+
+![4](4.png)
+
+Example 5:
+
+```text
+Input:
+[
+  "//",
+  "/ "
+]
+Output: 3
+Explanation: The 2x2 grid is as follows:
+```
+
+![5](5.png)
+
+Note:
+
+1. 1 <= grid.length == grid[0].length <= 30
+1. grid[i][j] is either '/', '\', or ' '.

Algorithms/0959.regions-cut-by-slashes/2.png

@@ -0,0 +1,75 @@
+package problem0959
+
+func regionsBySlashes(grid []string) int {
+	m := len(grid)
+	size := m * m * 4
+	u := newUnion(size)
+
+	// cut every square to 4 parts, and mark them
+	//    \0/
+	//   3 X 1
+	//    /2\
+	for i := 0; i < m; i++ {
+		for j := 0; j < m; j++ {
+			index := (i*m + j) * 4
+			top := index + 0
+			right := index + 1
+			down := index + 2
+			left := index + 3
+			switch grid[i][j] {
+			case '\\':
+				u.union(top, right)
+				u.union(down, left)
+			case '/':
+				u.union(top, left)
+				u.union(down, right)
+			default:
+				u.union(top, right)
+				u.union(right, down)
+				u.union(down, left)
+			}
+			// union right square' left
+			if rsl := index + 4 + 3; rsl < size {
+				u.union(right, rsl)
+			}
+			// union down square' top
+			if dst := index + 4*m; dst < size {
+				u.union(down, dst)
+			}
+		}
+	}
+
+	return u.count
+}
+
+type union struct {
+	parent []int
+	count  int
+}
+
+func newUnion(size int) *union {
+	parent := make([]int, size)
+	for i := range parent {
+		parent[i] = i
+	}
+	return &union{
+		parent: parent,
+		count:  size,
+	}
+}
+
+func (u *union) find(i int) int {
+	if u.parent[i] == i {
+		return i
+	}
+	u.parent[i] = u.find(u.parent[i])
+	return u.parent[i]
+}
+
+func (u *union) union(x, y int) {
+	xp, yp := u.find(x), u.find(y)
+	if xp != yp {
+		u.parent[yp] = xp
+		u.count--
+	}
+}

Algorithms/0959.regions-cut-by-slashes/3.png

@@ -0,0 +1,79 @@
+package problem0959
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// tcs is testcase slice
+var tcs = []struct {
+	grid []string
+	ans  int
+}{
+
+	{
+		[]string{
+			" /",
+			"/ ",
+		},
+		2,
+	},
+
+	{
+		[]string{
+			"/",
+		},
+		2,
+	},
+
+	{
+		[]string{
+			" /",
+			"  ",
+		},
+		1,
+	},
+
+	// {
+	// 	[]string{
+	// 		"\\/",
+	// 		"/\\",
+	// 	},
+	// 	4,
+	// },
+
+	// {
+	// 	[]string{
+	// 		"/\\",
+	// 		"\\/",
+	// 	},
+	// 	5,
+	// },
+
+	// {
+	// 	[]string{
+	// 		"//",
+	// 		"/ ",
+	// 	},
+	// 	3,
+	// },
+
+	// // 可以有多个 testcase
+}
+
+func Test_regionsBySlashes(t *testing.T) {
+	ast := assert.New(t)
+
+	for _, tc := range tcs {
+		ast.Equal(tc.ans, regionsBySlashes(tc.grid), "输入:%v", tc)
+	}
+}
+
+func Benchmark_regionsBySlashes(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range tcs {
+			regionsBySlashes(tc.grid)
+		}
+	}
+}

Algorithms/0959.regions-cut-by-slashes/4.png

@@ -1,7 +1,7 @@
 {
 	"Username": "aQuaYi",
 	"Ranking": 902,
-	"Updated": "2019-03-23T14:53:21.896823987+08:00",
+	"Updated": "2019-03-23T15:20:36.739536901+08:00",
 	"Record": {
 		"Easy": {
 			"Solved": 215,
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 			"Title": "Minimum Number of K Consecutive Bit Flips",
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