Merge pull request #820 from 0xff-dev/851

Add solution and test-cases for problem 851

Author: 6boris

leetcode/801-900/0851.Loud-and-Rich/README.md

@@ -1,28 +1,32 @@
 # [851.Loud and Rich][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 is a group of `n` people labeled from `0` to `n - 1` where each person has a different amount of money and a different level of quietness.
+
+You are given an array `richer` where `richer[i] = [ai, bi]` indicates that a<sub>i</sub> has more money than b<sub>i</sub> and an integer array `quiet` where `quiet[i]` is the quietness of the i<sup>th</sup> person. All the given data in richer are **logically correct** (i.e., the data will not lead you to a situation where `x` is richer than `y` and `y` is richer than `x` at the same time).
+
+Return an integer array `answer` where `answer[x] = y` if `y` is the least quiet person (that is, the person `y` with the smallest value of `quiet[y]`) among all people who definitely have equal to or more money than the person `x`.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: richer = [[1,0],[2,1],[3,1],[3,7],[4,3],[5,3],[6,3]], quiet = [3,2,5,4,6,1,7,0]
+Output: [5,5,2,5,4,5,6,7]
+Explanation: 
+answer[0] = 5.
+Person 5 has more money than 3, which has more money than 1, which has more money than 0.
+The only person who is quieter (has lower quiet[x]) is person 7, but it is not clear if they have more money than person 0.
+answer[7] = 7.
+Among all people that definitely have equal to or more money than person 7 (which could be persons 3, 4, 5, 6, or 7), the person who is the quietest (has lower quiet[x]) is person 7.
+The other answers can be filled out with similar reasoning.
 ```
 
-## 题意
-> ...
+**Example 2:**
 
-## 题解
-
-### 思路1
-> ...
-Loud and Rich
-```go
 ```
-
+Input: richer = [], quiet = [0]
+Output: [0]
+```
 
 ## 结语
 

leetcode/801-900/0851.Loud-and-Rich/Solution.go

@@ -1,5 +1,39 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(richer [][]int, quiet []int) []int {
+	l := len(quiet)
+	ans := make([]int, l)
+	greater := make([][]bool, l)
+	for i := 0; i < l; i++ {
+		greater[i] = make([]bool, l)
+	}
+
+	for _, cmp := range richer {
+		greater[cmp[1]][cmp[0]] = true
+	}
+
+	cache := make(map[int]int)
+	var dfs func(int) int
+	dfs = func(x int) int {
+		if v, ok := cache[x]; ok {
+			return v
+		}
+		ans := x
+		for u, v := range greater[x] {
+			if v {
+				if quiet[u] < quiet[ans] {
+					ans = u
+				}
+				if r := dfs(u); quiet[ans] > quiet[r] {
+					ans = r
+				}
+			}
+		}
+		cache[x] = ans
+		return ans
+	}
+	for i := 0; i < l; i++ {
+		ans[i] = dfs(i)
+	}
+	return ans
 }

leetcode/801-900/0851.Loud-and-Rich/Solution_test.go

@@ -10,30 +10,33 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		richer [][]int
+		quiet  []int
+		expect []int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", [][]int{
+			{1, 0}, {2, 1}, {3, 1},
+			{3, 7}, {4, 3}, {5, 3}, {6, 3},
+		}, []int{3, 2, 5, 4, 6, 1, 7, 0}, []int{5, 5, 2, 5, 4, 5, 6, 7}},
+		{"TestCase2", [][]int{}, []int{0}, []int{0}},
 	}
 
 	//	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.richer, c.quiet)
 			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.richer, c.quiet)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }