feat: add go solution to lcof2 problem: No.114 (#3582)

Author: taoyq1988

lcof2/剑指 Offer II 114. 外星文字典/README.md

@@ -287,6 +287,68 @@ public:
 };
 ```
 
+#### Go
+
+```go
+func alienOrder(words []string) string {
+	n := len(words)
+	if n == 0 {
+		return ""
+	}
+	if n == 1 {
+		return words[0]
+	}
+	inDegree := make(map[byte]int)
+	graph := make(map[byte][]byte)
+	for _, word := range words {
+		for i := 0; i < len(word); i++ {
+			inDegree[word[i]] = 0
+		}
+	}
+	for i := 0; i < n-1; i++ {
+		w1, w2 := words[i], words[i+1]
+		minLen := len(w1)
+		if len(w2) < minLen {
+			minLen = len(w2)
+		}
+		foundDifference := false
+		for j := 0; j < minLen; j++ {
+			if w1[j] != w2[j] {
+				inDegree[w2[j]]++
+				graph[w1[j]] = append(graph[w1[j]], w2[j])
+				foundDifference = true
+				break
+			}
+		}
+		if !foundDifference && len(w1) > len(w2) {
+			return ""
+		}
+	}
+	queue := make([]byte, 0)
+	for k := range inDegree {
+		if inDegree[k] == 0 {
+			queue = append(queue, k)
+		}
+	}
+	res := make([]byte, 0)
+	for len(queue) > 0 {
+		node := queue[0]
+		queue = queue[1:]
+		res = append(res, node)
+		for _, next := range graph[node] {
+			inDegree[next]--
+			if inDegree[next] == 0 {
+				queue = append(queue, next)
+			}
+		}
+	}
+	if len(res) != len(inDegree) {
+		return ""
+	}
+	return string(res)
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof2/剑指 Offer II 114. 外星文字典/Solution.go

@@ -0,0 +1,57 @@
+func alienOrder(words []string) string {
+	n := len(words)
+	if n == 0 {
+		return ""
+	}
+	if n == 1 {
+		return words[0]
+	}
+	inDegree := make(map[byte]int)
+	graph := make(map[byte][]byte)
+	for _, word := range words {
+		for i := 0; i < len(word); i++ {
+			inDegree[word[i]] = 0
+		}
+	}
+	for i := 0; i < n-1; i++ {
+		w1, w2 := words[i], words[i+1]
+		minLen := len(w1)
+		if len(w2) < minLen {
+			minLen = len(w2)
+		}
+		foundDifference := false
+		for j := 0; j < minLen; j++ {
+			if w1[j] != w2[j] {
+				inDegree[w2[j]]++
+				graph[w1[j]] = append(graph[w1[j]], w2[j])
+				foundDifference = true
+				break
+			}
+		}
+		if !foundDifference && len(w1) > len(w2) {
+			return ""
+		}
+	}
+	queue := make([]byte, 0)
+	for k := range inDegree {
+		if inDegree[k] == 0 {
+			queue = append(queue, k)
+		}
+	}
+	res := make([]byte, 0)
+	for len(queue) > 0 {
+		node := queue[0]
+		queue = queue[1:]
+		res = append(res, node)
+		for _, next := range graph[node] {
+			inDegree[next]--
+			if inDegree[next] == 0 {
+				queue = append(queue, next)
+			}
+		}
+	}
+	if len(res) != len(inDegree) {
+		return ""
+	}
+	return string(res)
+}