| author | Christian Urban <christian dot urban at kcl dot ac dot uk> | 
| Tue, 26 Sep 2017 14:08:49 +0100 | |
| changeset 504 | 3390e863d796 | 
| parent 471 | e5df48ff7033 | 
| child 525 | e5a004ffa681 | 
| permissions | -rw-r--r-- | 
| 
365
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
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1  | 
def concat(A: Set[String], B: Set[String]) : Set[String] =  | 
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9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
2  | 
for (x <-A ; y <- B) yield x ++ y  | 
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
3  | 
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9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
4  | 
def pow(A: Set[String], n: Int) : Set[String] = n match {
 | 
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9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
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5  | 
  case 0 => Set("")
 | 
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9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
6  | 
case n => concat(A, pow(A, n- 1))  | 
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9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
7  | 
}  | 
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9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
8  | 
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9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
9  | 
val A = Set("a", "b", "c", "d")
 | 
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
10  | 
pow(A, 4).size // -> 256  | 
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
11  | 
|
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
12  | 
val B = Set("a", "b", "c", "")
 | 
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
13  | 
pow(B, 4).size // -> 121  | 
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
14  | 
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| 471 | 15  | 
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16  | 
||
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397
 
cf3ca219c727
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents: 
365 
diff
changeset
 | 
17  | 
val B2 = Set("a", "b", "c", "")
 | 
| 
 
cf3ca219c727
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents: 
365 
diff
changeset
 | 
18  | 
pow(B2, 3).size // -> 40  | 
| 
 
cf3ca219c727
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents: 
365 
diff
changeset
 | 
19  | 
|
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365
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
20  | 
val C = Set("a", "b", "")
 | 
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
21  | 
pow(C, 2)  | 
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
22  | 
pow(C, 2).size // -> 7  | 
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
23  | 
|
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
24  | 
pow(C, 3)  | 
| 
 
9b71dead1219
updated
 
Christian Urban <christian dot urban at kcl dot ac dot uk> 
parents:  
diff
changeset
 | 
25  | 
pow(C, 3).size // -> 15  |