如何打印n個數的總和？

解決方法

下麵的示例演示如何使用堆棧的概念，首先添加n個自然數。

import java.io.IOException;

public class AdditionStack {
   static int num;
   static int ans;
   static Stack theStack;
   public static void main(String[] args)
   throws IOException {
      num = 50;
      stackAddition();
      System.out.println("Sum=" + ans);
   }
   public static void stackAddition() {
      theStack = new Stack(10000); 
      ans = 0; 
      while (num > 0) {
         theStack.push(num); 
         --num; 
      }
      while (!theStack.isEmpty()) {
         int newN = theStack.pop(); 
         ans += newN; 
      }
   }
}

class Stack {
   private int maxSize; 
   private int[] data;
   private int top; 
   public Stack(int s) {
      maxSize = s;
      data = new int[maxSize];
      top = -1;
   }
   public void push(int p) {
      data[++top] = p;
   }
   public int pop() {
      return data[top--];
   }
   public int peek() {
      return data[top];
   }
   public boolean isEmpty() {
      return (top == -1);
   }
}

結果

上麵的代碼示例將產生以下結果。

Sum=1225