2024/9/16 LeetCode Hot100 Stack

src/main/java/com/cool/hot100/stack/MinStack.java

@@ -0,0 +1,47 @@
+package com.cool.hot100.stack;
+
+import java.util.Stack;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/16/13:55
+ * DayNumber 1
+ * Hard 2
+ * Level 4
+ * @Description LeetCode 151题
+ */
+public class MinStack {
+    private Stack<Integer> stack;
+    private Stack<Integer> minStack;
+
+    public MinStack() {
+        stack=new Stack<>();
+        minStack=new Stack<>();
+    }
+
+    public void push(int val) {
+        stack.push(val);
+        if(minStack.isEmpty()||minStack.peek()>=val){
+            minStack.push(val);
+        }
+    }
+
+    public void pop() {
+
+        if(stack.pop().equals(minStack.peek())){
+            minStack.pop();
+        }
+    }
+
+    public int top() {
+        return stack.peek();
+    }
+
+    public int getMin() {
+        return minStack.peek();
+    }
+
+
+}

src/main/java/com/cool/hot100/stack/Num394.java

@@ -0,0 +1,41 @@
+package com.cool.hot100.stack;
+
+import java.util.Stack;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/16/17:52
+ * DayNumber 2
+ * Hard 2
+ * Level 6
+ */
+public class Num394 {
+    public String decodeString(String s) {
+        StringBuilder res = new StringBuilder();
+        int multi = 0;
+        Stack<Integer> multiStack = new Stack<>();
+        Stack<String> resStack = new Stack<>();
+        for (char c : s.toCharArray()) {
+            if (c == '[') {
+                multiStack.push(multi);
+                multi = 0;
+                resStack.push(res.toString());
+                res = new StringBuilder();
+            } else if (c == ']') {
+                int currentMulti = multiStack.pop();
+                StringBuilder temp = new StringBuilder();
+                for (int i = 0; i < currentMulti; i++) {
+                    temp.append(res);
+                }
+                res = new StringBuilder(resStack.pop() + temp);
+            } else if (c >= '0' && c <= '9') {
+                multi = multi * 10 + Integer.parseInt(c + "");
+            } else {
+                res.append(c);
+            }
+        }
+        return res.toString();
+    }
+}