Merge pull request #630 from 0xff-dev/720

Add solution and test-cases for problem 720

leetcode/701-800/0720.Longest-Word-in-Dictionary/README.md

@@ -1,28 +1,27 @@
 # [720.Longest Word in Dictionary][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
+Given an array of strings `words` representing an English Dictionary, return the longest word in `words` that can be built one character at a time by other `words` in words.
+
+If there is more than one possible answer, return the longest word with the smallest lexicographical order. If there is no answer, return the empty string.
+
+Note that the word should be built from left to right with each additional character being added to the end of a previous word. 
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: words = ["w","wo","wor","worl","world"]
+Output: "world"
+Explanation: The word "world" can be built one character at a time by "w", "wo", "wor", and "worl".
 ```
 
-## 题意
-> ...
+**Example 2:**
 
-## 题解
-
-### 思路1
-> ...
-Longest Word in Dictionary
-```go
 ```
-
+Input: words = ["a","banana","app","appl","ap","apply","apple"]
+Output: "apple"
+Explanation: Both "apply" and "apple" can be built from other words in the dictionary. However, "apple" is lexicographically smaller than "apply".
+```
 
 ## 结语
 

leetcode/701-800/0720.Longest-Word-in-Dictionary/Solution.go

@@ -1,5 +1,28 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "sort"
+
+func Solution(words []string) string {
+	sort.Slice(words, func(i, j int) bool {
+		li, lj := len(words[i]), len(words[j])
+		if li == lj {
+			return words[i] < words[j]
+		}
+		return li < lj
+	})
+	ok := make(map[string]struct{})
+	ans := ""
+	ok[ans] = struct{}{}
+	for _, w := range words {
+		lp := len(w)
+		pre := w[:lp-1]
+		if _, nice := ok[pre]; nice {
+			ok[w] = struct{}{}
+			if lp > len(ans) || (lp == len(ans) && w < ans) {
+				ans = w
+			}
+		}
+	}
+
+	return ans
 }

leetcode/701-800/0720.Longest-Word-in-Dictionary/Solution_test.go

@@ -10,12 +10,11 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs []string
+		expect string
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []string{"a", "banana", "app", "appl", "ap", "apply", "apple"}, "apple"},
+		{"TestCase2", []string{"w", "wo", "wor", "worl", "world"}, "world"},
 	}
 
 	//	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() {
 }