aboutsummaryrefslogtreecommitdiff
path: root/iterator_for_combination.py
diff options
context:
space:
mode:
Diffstat (limited to 'iterator_for_combination.py')
-rw-r--r--iterator_for_combination.py59
1 files changed, 59 insertions, 0 deletions
diff --git a/iterator_for_combination.py b/iterator_for_combination.py
new file mode 100644
index 0000000..699bb3d
--- /dev/null
+++ b/iterator_for_combination.py
@@ -0,0 +1,59 @@
+# 1286. Iterator for Combination
+
+"""
+design the 'CombinationIterator' class:
+- 'CombinationIterator(string characters, int combinationLength)' initialises
+the object with a string 'characters' of sorted distinct lowercase english
+letters and a number 'combinationLength' as arguments
+- 'next()' returns the next combination of length 'combinationLength' in
+lexicographical order
+- 'hasNext()' returns 'true' iff there exists a next combination
+"""
+
+
+class CombinationIterator(object):
+ def __init__(self, characters, combinationLength):
+ """
+ :type characters: str
+ :type combinationLength: int
+ """
+ self.characters = characters
+ self.n = len(characters)
+ self.combinations = self.get_comb(self.n, combinationLength)
+ self.idx = len(self.combinations) - 1
+
+ def next(self):
+ """
+ :rtype: str
+ """
+ s = ""
+ for i in range(self.n):
+ if self.combinations[self.idx][i] != "0":
+ s += self.characters[i]
+ self.idx -= 1
+ return s
+
+ def hasNext(self):
+ """
+ :rtype: bool
+ """
+ return self.idx > -1
+
+ def get_comb(self, l, n):
+ end = int("1" * l, 2)
+ res = []
+ for i in range(end + 1):
+ b = bin(i)[2:]
+ if b.count("1") == n:
+ res.append(b.zfill(l))
+ return res
+
+
+if __name__ == "__main__":
+ obj = CombinationIterator("abc", 2)
+ print(obj.next())
+ print(obj.hasNext())
+ print(obj.next())
+ print(obj.hasNext())
+ print(obj.next())
+ print(obj.hasNext())