规范格式

leetcode/1202.Smallest-String-With-Swaps/1202. Smallest String With Swaps.go

@@ -0,0 +1,31 @@
+package leetcode
+
+import (
+	"sort"
+
+	"github.com/halfrost/LeetCode-Go/template"
+)
+
+func smallestStringWithSwaps(s string, pairs [][]int) string {
+	uf, res, sMap := template.UnionFind{}, []byte(s), map[int][]byte{}
+	uf.Init(len(s))
+	for _, pair := range pairs {
+		uf.Union(pair[0], pair[1])
+	}
+	for i := 0; i < len(s); i++ {
+		r := uf.Find(i)
+		sMap[r] = append(sMap[r], s[i])
+	}
+	for _, v := range sMap {
+		sort.Slice(v, func(i, j int) bool {
+			return v[i] < v[j]
+		})
+	}
+	for i := 0; i < len(s); i++ {
+		r := uf.Find(i)
+		bytes := sMap[r]
+		res[i] = bytes[0]
+		sMap[r] = bytes[1:len(bytes)]
+	}
+	return string(res)
+}

leetcode/1202.Smallest-String-With-Swaps/1202. Smallest String With Swaps_test.go

@@ -0,0 +1,53 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question1202 struct {
+	para1202
+	ans1202
+}
+
+// para 是参数
+// one 代表第一个参数
+type para1202 struct {
+	s     string
+	pairs [][]int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans1202 struct {
+	one string
+}
+
+func Test_Problem1202(t *testing.T) {
+
+	qs := []question1202{
+
+		question1202{
+			para1202{"dcab", [][]int{[]int{0, 3}, []int{1, 2}}},
+			ans1202{"bacd"},
+		},
+
+		question1202{
+			para1202{"dcab", [][]int{[]int{0, 3}, []int{1, 2}, []int{0, 2}}},
+			ans1202{"abcd"},
+		},
+
+		question1202{
+			para1202{"cba", [][]int{[]int{0, 1}, []int{1, 2}}},
+			ans1202{"abc"},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 1202------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans1202, q.para1202
+		fmt.Printf("【input】:%v       【output】:%v\n", p, smallestStringWithSwaps(p.s, p.pairs))
+	}
+	fmt.Printf("\n\n\n")
+}

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

@@ -0,0 +1,63 @@
+# [1202. Smallest String With Swaps](https://leetcode.com/problems/smallest-string-with-swaps/)
+
+
+## 题目:
+
+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: 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"
+
+**Example 2:**
+
+    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"
+
+**Constraints:**
+
+- `1 <= s.length <= 10^5`
+- `0 <= pairs.length <= 10^5`
+- `0 <= pairs[i][0], pairs[i][1] < s.length`
+- `s` only contains lower case English letters.
+
+
+## 题目大意
+
+给你一个字符串 s，以及该字符串中的一些「索引对」数组 pairs，其中 pairs[i] = [a, b] 表示字符串中的两个索引（编号从 0 开始）。你可以 任意多次交换 在 pairs 中任意一对索引处的字符。返回在经过若干次交换后，s 可以变成的按字典序最小的字符串。
+
+提示：
+
+- 1 <= s.length <= 10^5
+- 0 <= pairs.length <= 10^5
+- 0 <= pairs[i][0], pairs[i][1] < s.length
+- s 中只含有小写英文字母
+
+
+
+## 解题思路
+
+
+- 给出一个字符串和一个字符串里可交换的下标。要求交换以后字典序最小的字符串。
+- 这一题可以用并查集来解题，先把可交换下标都 `Union()` 起来，每个集合内，按照字典序从小到大排列。最后扫描原有字符串，从左到右依次找到各自对应的集合里面最小的字符进行替换，每次替换完以后，删除集合中该字符(防止下次重复替换)。最终得到的字符就是最小字典序的字符。