Create 433.minimum-genetic-mutation.go

Week_04/433.minimum-genetic-mutation.go

@@ -0,0 +1,37 @@
+func minMutation(start string, end string, bank []string) int {
+    bankMap := make(map[string]struct{}, len(bank))
+    for i := range bank { bankMap[bank[i]] = struct{}{} }
+
+    if _, ok := bankMap[end]; !ok { return -1 }
+
+    changeMap := map[byte][]byte{
+        'A': []byte{'C', 'G', 'T'},
+        'C': []byte{'A', 'G', 'T'},
+        'G': []byte{'A', 'C', 'T'},
+        'T': []byte{'A', 'C', 'G'},
+    }
+
+    queue := []string{ start }
+    step := 0
+    for len(queue) > 0 {
+        n := len(queue)
+        for i := 0; i < n; i++ {
+            start = queue[0]
+            queue = queue[1:]
+            if start == end { return step }
+            // 这里可以优化，只变更需要变更的字符;(最开始循环一遍字符串就知道哪些字符不一样，需要多少步)
+            for j := 0; j < len(start); j++ {
+                for _, c := range changeMap[start[j]] {
+                    arr := []byte(start)
+                    arr[j] = c
+                    tmp := string(arr)
+                    if _, ok := bankMap[tmp]; ok {
+                        queue = append(queue, tmp)
+                    }
+                }
+            }
+        }
+        step++
+    }
+    return -1
+}