Add solution and test-cases for problem 990

leetcode/901-1000/0990.Satisfiability-of-Equality-Equations/README.md

@@ -1,28 +1,26 @@
 # [990.Satisfiability of Equality Equations][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
+You are given an array of strings `equations` that represent relationships between variables where each string `equations[i]` is of length `4` and takes one of two different forms: `"xi==yi"` or `"xi!=yi"`.Here, `xi` and `yi` are lowercase letters (not necessarily different) that represent one-letter variable names.
+
+Return `true` if it is possible to assign integers to variable names so as to satisfy all the given equations, or `false` otherwise.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: equations = ["a==b","b!=a"]
+Output: false
+Explanation: If we assign say, a = 1 and b = 1, then the first equation is satisfied, but not the second.
+There is no way to assign the variables to satisfy both equations.
 ```
 
-## 题意
-> ...
-
-## 题解
+**Example 2:**
 
-### 思路1
-> ...
-Satisfiability of Equality Equations
-```go
 ```
-
+Input: equations = ["b==a","a==b"]
+Output: true
+Explanation: We could assign a = 1 and b = 1 to satisfy both equations.
+```
 
 ## 结语
 

leetcode/901-1000/0990.Satisfiability-of-Equality-Equations/Solution.go

@@ -1,5 +1,50 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+type unionFind990 struct {
+	father [26]int
+}
+
+func (u *unionFind990) findFather(x int) int {
+	if x != u.father[x] {
+		u.father[x] = u.findFather(u.father[x])
+	}
+	return u.father[x]
+}
+func (u *unionFind990) union(x, y int) {
+	fx := u.findFather(x)
+	fy := u.findFather(y)
+	if fx < fy {
+		u.father[fx] = fy
+	} else {
+		u.father[fy] = fx
+	}
+}
+
+func Solution(equations []string) bool {
+	uf := unionFind990{father: [26]int{}}
+	for i := range 26 {
+		uf.father[i] = i
+	}
+
+	for _, v := range equations {
+		eq := v[1:3]
+		a, b := int(v[0]-'a'), int(v[3]-'a')
+		if eq != "==" {
+			continue
+		}
+		uf.union(a, b)
+	}
+	for _, v := range equations {
+		eq := v[1:3]
+		a, b := int(v[0]-'a'), int(v[3]-'a')
+		if eq == "==" {
+			continue
+		}
+		fa := uf.findFather(a)
+		fb := uf.findFather(b)
+		if fa == fb {
+			return false
+		}
+	}
+	return true
 }

leetcode/901-1000/0990.Satisfiability-of-Equality-Equations/Solution_test.go

@@ -10,12 +10,11 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
+		inputs []string
 		expect bool
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []string{"a==b", "b!=a"}, false},
+		{"TestCase2", []string{"b==a", "a==b"}, true},
 	}
 
 	//	开始测试
@@ -30,10 +29,10 @@ 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() {
 }