Merge pull request #1142 from 0xff-dev/2523

Add solution and test-cases for problem 2523

Author: 6boris

leetcode/2501-2600/2523.Closest-Prime-Numbers-in-Range/README.md

@@ -0,0 +1,35 @@
+# [2523.Closest Prime Numbers in Range][title]
+
+## Description
+Given two positive integers `left` and `right`, find the two integers `num1` and `num2` such that:
+
+- `left <= num1 < num2 <= right`.
+- Both `num1` and `num2` are prime numbers.
+- `num2 - num1` is the **minimum** amongst all other pairs satisfying the above conditions.
+
+Return the positive integer array `ans = [num1, num2]`. If there are multiple pairs satisfying these conditions, return the one with the **smallest** `num1` value. If no such numbers exist, return `[-1, -1]`.
+
+**Example 1:**
+
+```
+Input: left = 10, right = 19
+Output: [11,13]
+Explanation: The prime numbers between 10 and 19 are 11, 13, 17, and 19.
+The closest gap between any pair is 2, which can be achieved by [11,13] or [17,19].
+Since 11 is smaller than 17, we return the first pair.
+```
+
+**Example 2:**
+
+```
+Input: left = 4, right = 6
+Output: [-1,-1]
+Explanation: There exists only one prime number in the given range, so the conditions cannot be satisfied.
+```
+
+## 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/closest-prime-numbers-in-range
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/2501-2600/2523.Closest-Prime-Numbers-in-Range/Solution.go

@@ -1,5 +1,46 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "sort"
+
+func calPrime(max int) []int {
+	isPrime := make([]bool, max+1)
+
+	for i := 2; i <= max; i++ {
+		isPrime[i] = true
+	}
+
+	for i := 2; i*i <= max; i++ {
+		if isPrime[i] {
+			for j := i * i; j <= max; j += i {
+				isPrime[j] = false
+			}
+		}
+	}
+
+	var primes []int
+	for i := 2; i <= max; i++ {
+		if isPrime[i] {
+			primes = append(primes, i)
+		}
+	}
+
+	return primes
+}
+
+func Solution(left int, right int) []int {
+	res := []int{-1, -1}
+	primes := calPrime(right)
+	start := sort.Search(len(primes), func(i int) bool {
+		return primes[i] >= left
+	})
+	l := primes[start:]
+	m := -1
+	for i := 1; i < len(l); i++ {
+		if m == -1 || l[i]-l[i-1] < m {
+			m = l[i] - l[i-1]
+			res[0] = l[i-1]
+			res[1] = l[i]
+		}
+	}
+	return res
 }

leetcode/2501-2600/2523.Closest-Prime-Numbers-in-Range/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
+		left, right int
+		expect      []int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", 10, 19, []int{11, 13}},
+		{"TestCase2", 4, 6, []int{-1, -1}},
+		{"TestCase3", 1, 1000000, []int{2, 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.left, c.right)
 			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.left, c.right)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }