二刷155

Author: diguage

docs/0000-23-monotonic-stack.adoc

@@ -5,11 +5,13 @@
 
 . xref:0042-trapping-rain-water.adoc[42. Trapping Rain Water]
 . xref:0084-largest-rectangle-in-histogram.adoc[84. Largest Rectangle in Histogram]
+. xref:0155-min-stack.adoc[155. Min Stack] -- 这个辅助栈也可以认为是一种单调栈。
 . xref:0239-sliding-window-maximum.adoc[239. Sliding Window Maximum]
 . xref:0496-next-greater-element-i.adoc[496. Next Greater Element I]
 . xref:0503-next-greater-element-ii.adoc[503. Next Greater Element II]
 . xref:0654-maximum-binary-tree.adoc[654. Maximum Binary Tree]
 
+
 == 参考资料
 
 . https://cloud.tencent.com/developer/article/1998273[单调栈详解及其LeetCode应用详解^]

docs/0155-min-stack.adoc

@@ -3,10 +3,6 @@
 
 https://leetcode.com/problems/min-stack/[LeetCode - Min Stack^]
 
-这道题解法还挺多。只使用一个栈的方案，还需要再思考思考。
-
-TODO
-
 Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.
 
 
@@ -32,13 +28,39 @@ minStack.top();      --> Returns 0.
 minStack.getMin();   --> Returns -2.
 ----
 
- 
+== 思路分析
 
+使用两个栈，一个栈存原始数据，另外一个栈存当前栈的最小值。
 
+image::images/0155-01.gif[{image_attr}]
+
+// TODO 这道题解法还挺多。只使用一个栈的方案，还需要再思考思考。
 
 [[src-0155]]
+[tabs]
+====
+一刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0155_MinStack.java[tag=answer]
 ----
+--
+
+二刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0155_MinStack_2.java[tag=answer]
+----
+--
+====
+
+== 参考资料
+
+. https://leetcode.cn/problems/min-stack/solutions/242190/zui-xiao-zhan-by-leetcode-solution/[155. 最小栈 - 官方题解^]
+. https://leetcode.cn/problems/min-stack/solutions/13496/shi-yong-fu-zhu-zhan-tong-bu-he-bu-tong-bu-python-/[155. 最小栈 - 使用辅助栈（同步和不同步，Python 代码、Java 代码）^]
+
 

docs/images/0155-01.gif

@@ -337,6 +337,11 @@
 |{doc_base_url}/1644-lowest-common-ancestor-of-a-binary-tree-ii.adoc[题解]
 |树形DP套路，没有验证答案！
 
+|{counter:codes}
+|{leetcode_base_url}/min-stack/[155. Min Stack]
+|{doc_base_url}/0155-min-stack.adoc[题解]
+|复习单调栈
+
 |===
 
 截止目前，本轮练习一共完成 {codes} 道题。

logbook/202406.adoc

@@ -32,9 +32,11 @@
  * @since 2020-01-24 16:40
  */
 class _0155_MinStack {
+  // tag::answer[]
 
     // Runtime: 8 ms, faster than 18.94% of Java online submissions for Min Stack.
     // Memory Usage: 46.2 MB, less than 5.08% of Java online submissions for Min Stack.
+    // @author D瓜哥 · https://www.diguage.com
     private Stack<Integer> stack;
     private Stack<Integer> helper;
 

src/main/java/com/diguage/algo/leetcode/_0155_MinStack.java

@@ -0,0 +1,72 @@
+package com.diguage.algo.leetcode;
+
+import java.util.Deque;
+import java.util.LinkedList;
+import java.util.Stack;
+
+/**
+ * = 155. Min Stack
+ *
+ * https://leetcode.com/problems/min-stack/[Min Stack - LeetCode]
+ *
+ * Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.
+ *
+ * * push(x) -- Push element x onto stack.
+ * * pop() -- Removes the element on top of the stack.
+ * * top() -- Get the top element.
+ * * getMin() -- Retrieve the minimum element in the stack.
+ *
+ *
+ * .Example:
+ * [source]
+ * ----
+ * MinStack minStack = new MinStack();
+ * minStack.push(-2);
+ * minStack.push(0);
+ * minStack.push(-3);
+ * minStack.getMin();   --> Returns -3.
+ * minStack.pop();
+ * minStack.top();      --> Returns 0.
+ * minStack.getMin();   --> Returns -2.
+ * ----
+ *
+ * @author D瓜哥 · https://www.diguage.com
+ * @since 2020-01-24 16:40
+ */
+class _0155_MinStack_2 {
+  // tag::answer[]
+  private Deque<Integer> stack = new LinkedList<>();
+  private Deque<Integer> minStack = new LinkedList<>();
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2024-07-31 16:09:25
+   */
+  public void push(int x) {
+    stack.push(x);
+    if (minStack.isEmpty()) {
+      minStack.push(x);
+    } else {
+      if (x < minStack.peek()) {
+        minStack.push(x);
+      } else {
+        minStack.push(minStack.peek());
+      }
+    }
+  }
+
+  public void pop() {
+    stack.pop();
+    minStack.pop();
+  }
+
+  public int top() {
+    return stack.peek();
+  }
+
+  public int getMin() {
+    return minStack.peek();
+  }
+  // end::answer[]
+}
+
+