Merge pull request #924 from 0xff-dev/825

Add solution and test-cases for problem 825

Author: 6boris

leetcode/801-900/0825.Friends-Of-Appropriate-Ages/README.md

@@ -1,28 +1,43 @@
 # [825.Friends Of Appropriate Ages][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
+There are `n` persons on a social media website. You are given an integer array `ages` where `ages[i]` is the age of the i<sup>th</sup> person.
+
+A Person `x` will not send a friend request to a person `y` (`x != y`) if any of the following conditions is true:
+
+- `age[y] <= 0.5 * age[x] + 7`
+- `age[y] > age[x]`
+- `age[y] > 100 && age[x] < 100`
+
+Otherwise, `x` will send a friend request to `y`.
+
+Note that if `x` sends a request to `y`, `y` will not necessarily send a request to `x`. Also, a person will not send a friend request to themself.
+
+Return the total number of friend requests made.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: ages = [16,16]
+Output: 2
+Explanation: 2 people friend request each other.
 ```
 
-## 题意
-> ...
+**Example 2:**
 
-## 题解
-
-### 思路1
-> ...
-Friends Of Appropriate Ages
-```go
 ```
+Input: ages = [16,17,18]
+Output: 2
+Explanation: Friend requests are made 17 -> 16, 18 -> 17.
+```
+
+**Example 3:**
 
+```
+Input: ages = [20,30,100,110,120]
+Output: 3
+Explanation: Friend requests are made 110 -> 100, 120 -> 110, 120 -> 100.
+```
 
 ## 结语
 

leetcode/801-900/0825.Friends-Of-Appropriate-Ages/Solution.go

@@ -1,5 +1,41 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "sort"
+
+func Solution(ages []int) int {
+	count := make(map[int]int)
+	distinctAges := make([]int, 0)
+	for _, n := range ages {
+		count[n]++
+		if count[n] == 1 {
+			distinctAges = append(distinctAges, n)
+		}
+	}
+	sort.Ints(distinctAges)
+
+	ans := 0
+	for i := 1; i < len(distinctAges); i++ {
+		c := 0
+		for pre := i - 1; pre >= 0; pre-- {
+			if distinctAges[pre] <= distinctAges[i]/2+7 {
+				continue
+			}
+			if distinctAges[pre] > 100 && distinctAges[i] < 100 {
+				continue
+			}
+			c += count[distinctAges[pre]]
+		}
+		ans += c * count[distinctAges[i]]
+	}
+	for n, c := range count {
+		if c == 1 {
+			continue
+		}
+		if n <= n/2+7 {
+			continue
+		}
+		ans += (c - 1) * c
+	}
+
+	return ans
 }

leetcode/801-900/0825.Friends-Of-Appropriate-Ages/Solution_test.go

@@ -10,12 +10,13 @@ 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", []int{16, 16}, 2},
+		{"TestCase2", []int{16, 17, 18}, 2},
+		{"TestCase3", []int{20, 30, 100, 110, 120}, 3},
+		{"TestCase4", []int{54, 23, 102, 90, 40, 74, 112, 74, 76, 21}, 22},
 	}
 
 	//	开始测试
@@ -30,10 +31,10 @@ 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() {
 }