Create: 0895-maximum-frequency-stack.java

Adding a solution

Author: ChiragSharma0208

Diff for: java/0895-maximum-frequency-stack.java

@@ -0,0 +1,20 @@
+class FreqStack {
+    HashMap<Integer, Integer> freq = new HashMap<>();
+    HashMap<Integer, Stack<Integer>> m = new HashMap<>();
+    int maxfreq = 0;
+
+    public void push(int x) {
+        int f = freq.getOrDefault(x, 0) + 1;
+        freq.put(x, f);
+        maxfreq = Math.max(maxfreq, f);
+        if (!m.containsKey(f)) m.put(f, new Stack<Integer>());
+        m.get(f).add(x);
+    }
+
+    public int pop() {
+        int x = m.get(maxfreq).pop();
+        freq.put(x, maxfreq - 1);
+        if (m.get(maxfreq).size() == 0) maxfreq--;
+        return x;
+    }
+}