Update 0459.重复的子字符串.md 添加swift方法(前缀表统一不减一)

Author: Amberling1988

problems/0459.重复的子字符串.md

@@ -463,6 +463,46 @@ Swift:
         }
     }
 ```
+> 前缀表统一不减一
+```swift 
+	func repeatedSubstringPattern(_ s: String) -> Bool {
+        
+        let sArr = Array(s)
+        let len = sArr.count
+        if len == 0 {
+            return false
+        }
+        
+        var next = Array.init(repeating: 0, count: len)
+        getNext(&next, sArr)
+        
+        if next[len-1] != 0 && len % (len - next[len-1]) == 0 {
+            return true
+        }
+        
+        return false
+    }
+    
+    // 前缀表不减一
+    func getNext(_ next: inout [Int], _ sArr:[Character]) {
+        
+        var j = 0
+        next[0] = 0
+        
+        for  i  in 1 ..< sArr.count {
 
+            while j > 0 && sArr[i] != sArr[j] {
+                j = next[j-1]
+            }
+            
+            if sArr[i] == sArr[j] {
+                j += 1
+            }
+            
+            next[i] = j
+        }
+    }
+
+```
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