【Grind75Hard】11問目 895. Maximum Frequency Stack

grind75_hard/11_895. Maximum Frequency Stack/level_1.py

@@ -0,0 +1,21 @@
+# 回数ごとに違うstackを作る
+class FreqStack:
+
+    def __init__(self):
+        self.freq = defaultdict(int)
+        self.stack = [[]]
+        self.max_freq = 0
+
+    def push(self, val: int) -> None:
+        self.freq[val] += 1
+        if len(self.stack) < self.freq[val]:
+            self.stack.append([])
+        self.max_freq = max(self.max_freq, self.freq[val])
+        self.stack[self.freq[val] - 1].append(val)
+
+    def pop(self) -> int:
+        val = self.stack[self.max_freq - 1].pop()
+        self.freq[val] -= 1
+        if not self.stack[self.max_freq - 1]:
+            self.max_freq -= 1
+        return val

grind75_hard/11_895. Maximum Frequency Stack/level_2.py

@@ -0,0 +1,21 @@
+# stacksをdefaultdict(list)を使うことで空の場合の確認を不要にした。
+class FreqStack:
+
+    def __init__(self):
+        self.frequency = defaultdict(int)
+        self.stacks = defaultdict(list)
+        self.max_frequency = 0
+
+    def push(self, val: int) -> None:
+        self.frequency[val] += 1
+        self.max_frequency = max(self.max_frequency, self.frequency[val])
+        self.stacks[self.frequency[val]].append(val)
+
+    def pop(self) -> int:
+        if not self.stacks[self.max_frequency]:
+            return None
+        top_value = self.stacks[self.max_frequency].pop()
+        self.frequency[val] -= 1
+        while self.max_frequency != 0 and not self.stacks[self.max_frequency]:
+            self.max_frequency -= 1
+        return top_value

grind75_hard/11_895. Maximum Frequency Stack/level_3.py

@@ -0,0 +1,18 @@
+class FreqStack:
+
+    def __init__(self):
+        self.frequency = defaultdict(int)
+        self.stacks = defaultdict(list)
+        self.max_frequency = 0
+
+    def push(self, val: int) -> None:
+        self.frequency[val] += 1
+        self.stacks[self.frequency[val]].append(val)
+        self.max_frequency = max(self.max_frequency, self.frequency[val])
+
+    def pop(self) -> int:
+        value = self.stacks[self.max_frequency].pop()
+        self.frequency[value] -= 1
+        while self.max_frequency != 0 and not self.stacks[self.max_frequency]:
+            self.max_frequency -= 1
+        return value