Merge pull request #668 from 0xff-dev/1202

Add solution and test-cases for problem 1202

leetcode/1201-1300/1202.Smallest-String-With-Swaps/README.md

@@ -1,28 +1,43 @@
 # [1202.Smallest String With Swaps][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 a string `s`, and an array of pairs of indices in the string `pairs` where `pairs[i] = [a, b]` indicates 2 indices(0-indexed) of the string.
+
+You can swap the characters at any pair of indices in the given `pairs` **any number of times**.
+
+Return the lexicographically smallest string that `s` can be changed to after using the swaps.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: s = "dcab", pairs = [[0,3],[1,2]]
+Output: "bacd"
+Explaination: 
+Swap s[0] and s[3], s = "bcad"
+Swap s[1] and s[2], s = "bacd"
 ```
 
-## 题意
-> ...
-
-## 题解
+**Example 2:**
 
-### 思路1
-> ...
-Smallest String With Swaps
-```go
 ```
+Input: s = "dcab", pairs = [[0,3],[1,2],[0,2]]
+Output: "abcd"
+Explaination: 
+Swap s[0] and s[3], s = "bcad"
+Swap s[0] and s[2], s = "acbd"
+Swap s[1] and s[2], s = "abcd"
+```
+
+**Example 3:**
 
+```
+Input: s = "cba", pairs = [[0,1],[1,2]]
+Output: "abc"
+Explaination: 
+Swap s[0] and s[1], s = "bca"
+Swap s[1] and s[2], s = "bac"
+Swap s[0] and s[1], s = "abc"
+```
 
 ## 结语
 

leetcode/1201-1300/1202.Smallest-String-With-Swaps/Solution.go

@@ -1,5 +1,62 @@
 package Solution
 
-func Solution(x bool) bool {
+type unionFind1202 struct {
+	fatehr []int
+}
+
+func (u *unionFind1202) findFather(x int) int {
+	if u.fatehr[x] != x {
+		u.fatehr[x] = u.findFather(u.fatehr[x])
+	}
+	return u.fatehr[x]
+}
+func (u *unionFind1202) union(x, y int) {
+	fx := u.findFather(x)
+	fy := u.findFather(y)
+	if fx < fy {
+		u.fatehr[fy] = fx
+	} else {
+		u.fatehr[fx] = fy
+	}
+}
+
+type stroe1202 struct {
+	bytes [26]int
+	index int
+}
+
+func (s *stroe1202) selectByte() byte {
+	for s.bytes[s.index] == 0 {
+		s.index++
+	}
+	x := uint8(s.index) + 'a'
+	s.bytes[s.index]--
 	return x
 }
+
+func Solution(s string, pairs [][]int) string {
+	bs := []byte(s)
+	u := &unionFind1202{fatehr: make([]int, len(s))}
+	for i := 0; i < len(s); i++ {
+		u.fatehr[i] = i
+	}
+	for _, pair := range pairs {
+		u.union(pair[0], pair[1])
+	}
+
+	children := make(map[int]*stroe1202)
+	for idx := 0; idx < len(s); idx++ {
+		fidx := u.findFather(idx)
+		if _, ok := children[fidx]; !ok {
+			children[fidx] = &stroe1202{bytes: [26]int{}, index: 0}
+		}
+		children[fidx].bytes[bs[idx]-'a']++
+	}
+
+	for idx := 0; idx < len(bs); idx++ {
+		fidx := u.findFather(idx)
+		bs[idx] = children[fidx].selectByte()
+	}
+
+	return string(bs)
+}

leetcode/1201-1300/1202.Smallest-String-With-Swaps/Solution_test.go

@@ -10,30 +10,35 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs string
+		pairs  [][]int
+		expect string
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", "dcab", [][]int{{0, 3}, {1, 2}}, "bacd"},
+		{"TestCase2", "dcab", [][]int{
+			{0, 3}, {1, 2}, {0, 2},
+		}, "abcd"},
+		{"TestCase3", "cba", [][]int{
+			{0, 1}, {1, 2},
+		}, "abc"},
 	}
 
 	//	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.inputs, c.pairs)
 			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.inputs, c.pairs)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }