Merge pull request #1094 from 0xff-dev/2657

Add solution and test-cases for problem 2657

Author: 6boris

leetcode/2601-2700/2657.Find-the-Prefix-Common-Array-of-Two-Arrays/README.md

@@ -0,0 +1,38 @@
+# [2657.Find the Prefix Common Array of Two Arrays][title]
+
+## Description
+You are given two **0-indexed** integer permutations `A` and `B` of length `n`.
+
+A **prefix common array** of `A` and `B` is an array `C` such that `C[i]` is equal to the count of numbers that are present at or before the index `i` in both `A` and `B`.
+
+Return the **prefix common array** of `A` and `B`.
+
+A sequence of `n` integers is called a **permutation** if it contains all integers from `1` to `n` exactly once.
+
+**Example 1:**
+
+```
+Input: A = [1,3,2,4], B = [3,1,2,4]
+Output: [0,2,3,4]
+Explanation: At i = 0: no number is common, so C[0] = 0.
+At i = 1: 1 and 3 are common in A and B, so C[1] = 2.
+At i = 2: 1, 2, and 3 are common in A and B, so C[2] = 3.
+At i = 3: 1, 2, 3, and 4 are common in A and B, so C[3] = 4.
+```
+
+**Example 2:**
+
+```
+Input: A = [2,3,1], B = [3,1,2]
+Output: [0,1,3]
+Explanation: At i = 0: no number is common, so C[0] = 0.
+At i = 1: only 3 is common in A and B, so C[1] = 1.
+At i = 2: 1, 2, and 3 are common in A and B, so C[2] = 3.
+```
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-golang-algorithm][me]
+
+[title]: https://leetcode.com/problems/find-the-prefix-common-array-of-two-arrays
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/2601-2700/2657.Find-the-Prefix-Common-Array-of-Two-Arrays/Solution.go

@@ -1,5 +1,24 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(A []int, B []int) []int {
+	ans := make([]int, len(A))
+	count := make([]uint8, len(A)+1)
+	for i := 0; i < len(A); i++ {
+		if i > 0 {
+			ans[i] = ans[i-1]
+		}
+		count[A[i]]++
+		count[B[i]]++
+		if A[i] == B[i] {
+			ans[i]++
+			continue
+		}
+		if count[A[i]] == 2 {
+			ans[i]++
+		}
+		if count[B[i]] == 2 {
+			ans[i]++
+		}
+	}
+	return ans
 }

leetcode/2601-2700/2657.Find-the-Prefix-Common-Array-of-Two-Arrays/Solution_test.go

@@ -10,30 +10,29 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		a, b   []int
+		expect []int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{1, 3, 2, 4}, []int{3, 1, 2, 4}, []int{0, 2, 3, 4}},
+		{"TestCase2", []int{2, 3, 1}, []int{3, 1, 2}, []int{0, 1, 3}},
 	}
 
 	//	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.a, c.b)
 			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.a, c.b)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }