diff --git a/MCA算法突击课/第03期/ppt/key/第01节.key b/MCA算法突击课/第03期/ppt/key/第01节.key
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diff --git a/MCA算法突击课/第03期/ppt/key/第02节.key b/MCA算法突击课/第03期/ppt/key/第02节.key
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diff --git a/MCA算法突击课/第03期/ppt/powerpoint/第01节.pptx b/MCA算法突击课/第03期/ppt/powerpoint/第01节.pptx
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diff --git a/MCA算法突击课/第03期/ppt/powerpoint/第02节.pptx b/MCA算法突击课/第03期/ppt/powerpoint/第02节.pptx
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diff --git a/体系学习班/class03/Code05_GetMinStack.java b/体系学习班/class03/Code05_GetMinStack.java
index 91b20ae..9208e59 100644
--- a/体系学习班/class03/Code05_GetMinStack.java
+++ b/体系学习班/class03/Code05_GetMinStack.java
@@ -9,35 +9,33 @@ public class Code05_GetMinStack {
 		private Stack<Integer> stackMin;
 
 		public MyStack1() {
-			this.stackData = new Stack<Integer>();
-			this.stackMin = new Stack<Integer>();
+			stackData = new Stack<Integer>();
+			stackMin = new Stack<Integer>();
 		}
 
 		public void push(int newNum) {
-			if (this.stackMin.isEmpty()) {
-				this.stackMin.push(newNum);
-			} else if (newNum <= this.getmin()) {
-				this.stackMin.push(newNum);
+			if (stackMin.isEmpty() || newNum <= this.getmin()) {
+				stackMin.push(newNum);
 			}
-			this.stackData.push(newNum);
+			stackData.push(newNum);
 		}
 
 		public int pop() {
-			if (this.stackData.isEmpty()) {
+			if (stackData.isEmpty()) {
 				throw new RuntimeException("Your stack is empty.");
 			}
-			int value = this.stackData.pop();
-			if (value == this.getmin()) {
-				this.stackMin.pop();
+			int value = stackData.pop();
+			if (value == getmin()) {
+				stackMin.pop();
 			}
 			return value;
 		}
 
 		public int getmin() {
-			if (this.stackMin.isEmpty()) {
+			if (stackMin.isEmpty()) {
 				throw new RuntimeException("Your stack is empty.");
 			}
-			return this.stackMin.peek();
+			return stackMin.peek();
 		}
 	}
 
@@ -46,35 +44,32 @@ public class Code05_GetMinStack {
 		private Stack<Integer> stackMin;
 
 		public MyStack2() {
-			this.stackData = new Stack<Integer>();
-			this.stackMin = new Stack<Integer>();
+			stackData = new Stack<Integer>();
+			stackMin = new Stack<Integer>();
 		}
 
 		public void push(int newNum) {
-			if (this.stackMin.isEmpty()) {
-				this.stackMin.push(newNum);
-			} else if (newNum < this.getmin()) {
-				this.stackMin.push(newNum);
+			if (stackMin.isEmpty() || newNum < getmin()) {
+				stackMin.push(newNum);
 			} else {
-				int newMin = this.stackMin.peek();
-				this.stackMin.push(newMin);
+				stackMin.push(stackMin.peek());
 			}
-			this.stackData.push(newNum);
+			stackData.push(newNum);
 		}
 
 		public int pop() {
-			if (this.stackData.isEmpty()) {
+			if (stackData.isEmpty()) {
 				throw new RuntimeException("Your stack is empty.");
 			}
-			this.stackMin.pop();
-			return this.stackData.pop();
+			stackMin.pop();
+			return stackData.pop();
 		}
 
 		public int getmin() {
-			if (this.stackMin.isEmpty()) {
+			if (stackMin.isEmpty()) {
 				throw new RuntimeException("Your stack is empty.");
 			}
-			return this.stackMin.peek();
+			return stackMin.peek();
 		}
 	}
 
@@ -91,7 +86,7 @@ public class Code05_GetMinStack {
 
 		System.out.println("=============");
 
-		MyStack1 stack2 = new MyStack1();
+		MyStack2 stack2 = new MyStack2();
 		stack2.push(3);
 		System.out.println(stack2.getmin());
 		stack2.push(4);