Create 127.word-ladder.go

Week_04/127.word-ladder.go

@@ -0,0 +1,40 @@
+func ladderLength(beginWord string, endWord string, wordList []string) int {
+    words := make(map[string]int, len(wordList))
+    for i, word := range wordList { words[word] = i }
+    visited := make([]bool, len(wordList))  // 下标
+    if _, ok := words[endWord]; !ok {
+        return 0
+    }
+
+    step, length := 1, len(beginWord)
+    queue := []string{ beginWord }
+    for len(queue) > 0 {
+        size := len(queue)
+        for i := 0; i < size; i++ {
+            beginWord = queue[i]
+            if beginWord == endWord { return step }
+            chars := []byte(beginWord)
+            for j := 0; j < length; j++ {
+                o := chars[j]
+                for c := 'a'; c <= 'z'; c++ {
+                    chars[j] = byte(c)
+                    tmp := string(chars)
+                    if index, ok := words[tmp]; ok {
+                        if visited[index] {
+                            continue
+                        }
+                        visited[index] = true
+                        queue = append(queue, tmp)
+                    } else {
+                        continue
+                    }
+                }
+                chars[j] = o
+            }
+        }
+        queue = queue[size:]
+        step++
+    }
+
+    return 0
+}