Merge pull request #1052 from 0xff-dev/2337

Add solution and test-cases for problem 2337

Author: 6boris

leetcode/2301-2400/2337.Move-Pieces-to-Obtain-a-String/README.md

@@ -1,28 +1,41 @@
 # [2337.Move Pieces to Obtain a String][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
+You are given two strings `start` and `target`, both of length `n`. Each string consists **only** of the characters `'L'`, `'R'`, and `'_'` where:
+
+- The characters `'L'` and `'R'` represent pieces, where a piece `'L'` can move to the **left** only if there is a **blank** space directly to its left, and a piece `'R'` can move to the **right** only if there is a **blank** space directly to its right.
+- The character `'_'` represents a blank space that can be occupied by **any** of the `'L'` or `'R'` pieces.
+
+Return `true` if it is possible to obtain the string `target` by moving the pieces of the string `start` **any** number of times. Otherwise, return `false`.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: start = "_L__R__R_", target = "L______RR"
+Output: true
+Explanation: We can obtain the string target from start by doing the following moves:
+- Move the first piece one step to the left, start becomes equal to "L___R__R_".
+- Move the last piece one step to the right, start becomes equal to "L___R___R".
+- Move the second piece three steps to the right, start becomes equal to "L______RR".
+Since it is possible to get the string target from start, we return true.
 ```
 
-## 题意
-> ...
-
-## 题解
+**Example 2:**
 
-### 思路1
-> ...
-Move Pieces to Obtain a String
-```go
 ```
+Input: start = "R_L_", target = "__LR"
+Output: false
+Explanation: The 'R' piece in the string start can move one step to the right to obtain "_RL_".
+After that, no pieces can move anymore, so it is impossible to obtain the string target from start.
+```
+
+**Example 3:**
 
+```
+Input: start = "_R", target = "R_"
+Output: false
+Explanation: The piece in the string start can move only to the right, so it is impossible to obtain the string target from start.
+```
 
 ## 结语
 

leetcode/2301-2400/2337.Move-Pieces-to-Obtain-a-String/Solution.go

@@ -1,5 +1,42 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+type pair2337 struct {
+	c byte
+	i int
+}
+
+func Solution(start string, target string) bool {
+	a, b := make([]pair2337, 0), make([]pair2337, 0)
+	for i, c := range []byte(start) {
+		if c == '_' {
+			continue
+		}
+		a = append(a, pair2337{c, i})
+	}
+	for i, c := range []byte(target) {
+		if c == '_' {
+			continue
+		}
+		b = append(b, pair2337{c, i})
+	}
+	if len(a) != len(b) {
+		// _ 不相等，无法转换
+		return false
+	}
+
+	for i := range len(a) {
+		ac := a[i]
+		bc := b[i]
+		if ac.c != bc.c {
+			return false
+		}
+		// 如果我此时是L
+		if ac.c == 'L' && ac.i < bc.i {
+			return false
+		}
+		if ac.c == 'R' && ac.i > bc.i {
+			return false
+		}
+	}
+	return true
 }

leetcode/2301-2400/2337.Move-Pieces-to-Obtain-a-String/Solution_test.go

@@ -9,31 +9,31 @@ import (
 func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
-		name   string
-		inputs bool
-		expect bool
+		name          string
+		start, target string
+		expect        bool
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", "_L__R__R_", "L______RR", true},
+		{"TestCase2", "R_L_", "__LR", false},
+		{"TestCase3", "_R", "R_", false},
 	}
 
 	//	开始测试
 	for i, c := range cases {
 		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
-			got := Solution(c.inputs)
+			got := Solution(c.start, c.target)
 			if !reflect.DeepEqual(got, c.expect) {
-				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
-					c.expect, got, c.inputs)
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v %v",
+					c.expect, got, c.start, c.target)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }