Merge pull request #851 from 0xff-dev/788

Add solution and test-cases for problem 788

Author: 6boris

leetcode/701-800/0788.Rotated-Digits/README.md

@@ -1,28 +1,39 @@
 # [788.Rotated Digits][title]
 
-> [!WARNING|style:flat]
-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
-
 ## Description
+An integer `x` is a **good** if after rotating each digit individually by 180 degrees, we get a valid number that is different from `x`. Each digit must be rotated - we cannot choose to leave it alone.
+
+A number is valid if each digit remains a digit after rotation. For example:
+
+- `0`, `1`, and `8` rotate to themselves,
+- `2` and `5` rotate to each other (in this case they are rotated in a different direction, in other words, `2` or `5` gets mirrored),
+- `6` and `9` rotate to each other, and
+- the rest of the numbers do not rotate to any other number and become invalid.
+
+Given an integer `n`, return the number of **good** integers in the range `[1, n]`.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: n = 10
+Output: 4
+Explanation: There are four good numbers in the range [1, 10] : 2, 5, 6, 9.
+Note that 1 and 10 are not good numbers, since they remain unchanged after rotating.
 ```
 
-## 题意
-> ...
-
-## 题解
+**Example 2:**
 
-### 思路1
-> ...
-Rotated Digits
-```go
 ```
+Input: n = 1
+Output: 0
+```
+
+**Example 3:**
 
+```
+Input: n = 2
+Output: 1
+```
 
 ## 结语
 

leetcode/701-800/0788.Rotated-Digits/Solution.go

@@ -1,5 +1,31 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+var (
+	rotateMap = map[int]int{
+		0: 0, 1: 1, 8: 8,
+		2: 5, 5: 2, 6: 9, 9: 6,
+	}
+)
+
+func isNumOk(n int) bool {
+	ans := false
+	for n > 0 {
+		x := n % 10
+		v, ok := rotateMap[x]
+		if !ok {
+			return false
+		}
+		ans = ans || x != v
+		n /= 10
+	}
+	return ans
+}
+func Solution(n int) int {
+	ans := 0
+	for i := 1; i <= n; i++ {
+		if isNumOk(i) {
+			ans++
+		}
+	}
+	return ans
 }

leetcode/701-800/0788.Rotated-Digits/Solution_test.go

@@ -10,12 +10,12 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs int
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", 10, 4},
+		{"TestCase2", 1, 0},
+		{"TestCase3", 2, 1},
 	}
 
 	//	开始测试
@@ -30,10 +30,10 @@ func TestSolution(t *testing.T) {
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }