Merge pull request #885 from 0xff-dev/900

Add solution and test-cases for problem 900

Author: 6boris

leetcode/801-900/0900.RLE-Iterator/README.md

@@ -1,28 +1,34 @@
 # [900.RLE Iterator][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
+We can use run-length encoding (i.e., **RLE**) to encode a sequence of integers. In a run-length encoded array of even length `encoding` (**0-indexed**), for all even `i`, `encoding[i]` tells us the number of times that the non-negative integer value `encoding[i + 1]` is repeated in the sequence.
 
-**Example 1:**
+- For example, the sequence `arr = [8,8,8,5,5]` can be encoded to be `encoding = [3,8,2,5]`. `encoding = [3,8,0,9,2,5]` and `encoding = [2,8,1,8,2,5]` are also valid **RLE** of `arr`.
 
-```
-Input: a = "11", b = "1"
-Output: "100"
-```
+Given a run-length encoded array, design an iterator that iterates through it.
 
-## 题意
-> ...
+Implement the `RLEIterator` class:
 
-## 题解
+- `RLEIterator(int[] encoded)` Initializes the object with the encoded array `encoded`.
+- `int next(int n)` Exhausts the next `n` elements and returns the last element exhausted in this way. If there is no element left to exhaust, return `-1` instead.
 
-### 思路1
-> ...
-RLE Iterator
-```go
-```
+**Example 1:**
 
+```
+Input
+["RLEIterator", "next", "next", "next", "next"]
+[[[3, 8, 0, 9, 2, 5]], [2], [1], [1], [2]]
+Output
+[null, 8, 8, 5, -1]
+
+Explanation
+RLEIterator rLEIterator = new RLEIterator([3, 8, 0, 9, 2, 5]); // This maps to the sequence [8,8,8,5,5].
+rLEIterator.next(2); // exhausts 2 terms of the sequence, returning 8. The remaining sequence is now [8, 5, 5].
+rLEIterator.next(1); // exhausts 1 term of the sequence, returning 8. The remaining sequence is now [5, 5].
+rLEIterator.next(1); // exhausts 1 term of the sequence, returning 5. The remaining sequence is now [5].
+rLEIterator.next(2); // exhausts 2 terms, returning -1. This is because the first term exhausted was 5,
+but the second term did not exist. Since the last term exhausted does not exist, we return -1.
+```
 
 ## 结语
 

leetcode/801-900/0900.RLE-Iterator/Solution.go

@@ -1,5 +1,38 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+type RLEIterator struct {
+	source []int
+	index  int
+}
+
+func Constructor900(encoding []int) RLEIterator {
+	rle := RLEIterator{source: make([]int, 0), index: 0}
+	for i := 0; i < len(encoding)-1; i += 2 {
+		if encoding[i] == 0 {
+			continue
+		}
+		rle.source = append(rle.source, encoding[i], encoding[i+1])
+	}
+	return rle
+}
+
+func (this *RLEIterator) Next(n int) int {
+	for ; this.index < len(this.source)-1 && this.source[this.index] < n; this.index += 2 {
+		n -= this.source[this.index]
+		this.source[this.index] = 0
+	}
+	if this.index == len(this.source) {
+		return -1
+	}
+	this.source[this.index] -= n
+	return this.source[this.index+1]
+}
+
+func Solution(encodings []int, input []int) []int {
+	c := Constructor900(encodings)
+	ans := make([]int, len(input))
+	for i, n := range input {
+		ans[i] = c.Next(n)
+	}
+	return ans
 }

leetcode/801-900/0900.RLE-Iterator/Solution_test.go

@@ -9,31 +9,29 @@ import (
 func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
-		name   string
-		inputs bool
-		expect bool
+		name             string
+		encodings, input []int
+		expect           []int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{3, 8, 0, 9, 2, 5}, []int{2, 1, 1, 2}, []int{8, 8, 5, -1}},
 	}
 
 	//	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.encodings, c.input)
 			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.encodings, c.input)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }