Class 4 1.Write a Java code to return the string after removing all ‘b’ (except the last and the one before the last) from a given string.
时间: 2024-05-04 09:15:56 浏览: 7
好的,让我来回答你的问题。
以下是实现该功能的Java代码:
```
public static String removeB(String str) {
int len = str.length();
StringBuilder sb = new StringBuilder(len);
int count = 0;
for (int i = 0; i < len; i++) {
char c = str.charAt(i);
if (c == 'b' && count < len - 2) {
count++;
} else {
sb.append(c);
}
}
return sb.toString();
}
```
代码中定义了一个字符串构建器StringBuilder,遍历给定字符串中的每个字符,如果该字符为‘b’且不是倒数第一或倒数第二个字符,则计数器加1,反之则向构建器中添加该字符。最后返回构建器中的字符串。
这是一个简单的字符串操作,代码很容易理解。如果您有任何疑问,请继续问我。
相关问题
Similarly, show how the library function init that removes the last element from a list can be defined in two different ways.
Sure! The library function `init` that removes the last element from a list can be defined in two different ways.
Method 1: Using list slicing
```python
def init(list):
return list[:-1]
```
This method uses list slicing to return all elements of the list except the last one. It creates a new list without modifying the original list.
Method 2: Using list comprehension
```python
def init(list):
return [list[i] for i in range(len(list) - 1)]
```
This method uses list comprehension to iterate over the indices of the list and construct a new list containing all elements except the last one.
Both methods achieve the same result of removing the last element from the list. You can choose the method that best suits your coding style or requirements.
Define Stack and its operations. Write java program to perform stack operations. (Explanation, Algorithm, Java source code)
A stack is a linear data structure that follows a particular order in which the operations are performed. The order is known as LIFO (Last In First Out). This means that the element which is pushed last onto the stack will be the first one to be popped off the stack.
Stack operations include:
1. push - adds an element to the top of the stack
2. pop - removes the top element from the stack
3. peek - returns the top element of the stack without removing it
4. isEmpty - checks if the stack is empty
5. isFull - checks if the stack is full
Java program to perform stack operations:
```
class Stack {
private int maxSize;
private int[] stackArray;
private int top;
public Stack(int size) {
maxSize = size;
stackArray = new int[maxSize];
top = -1;
}
public void push(int value) {
if (isFull()) {
System.out.println("Stack is full!");
return;
}
top++;
stackArray[top] = value;
}
public int pop() {
if (isEmpty()) {
System.out.println("Stack is empty!");
return -1;
}
int temp = stackArray[top];
top--;
return temp;
}
public int peek() {
return stackArray[top];
}
public boolean isEmpty() {
return (top == -1);
}
public boolean isFull() {
return (top == maxSize - 1);
}
}
public class Main {
public static void main(String[] args) {
Stack stack = new Stack(5);
stack.push(10);
stack.push(20);
stack.push(30);
System.out.println("Top element: " + stack.peek());
stack.push(40);
stack.push(50);
System.out.println("Full: " + stack.isFull());
while (!stack.isEmpty()) {
int value = stack.pop();
System.out.println(value);
}
System.out.println("Empty: " + stack.isEmpty());
}
}
```
Explanation:
In this program, we have defined a `Stack` class that contains all the necessary stack operations - `push`, `pop`, `peek`, `isEmpty`, and `isFull`. The `Stack` class also has three instance variables - `maxSize`, `stackArray`, and `top`.
In the `push` method, we first check if the stack is already full. If it is, we print a message and return. Otherwise, we increment the `top` variable and add the new element to the `stackArray`.
In the `pop` method, we first check if the stack is empty. If it is, we print a message and return -1. Otherwise, we retrieve the top element from the `stackArray`, decrement the `top` variable, and return the element.
In the `peek` method, we simply return the top element from the `stackArray`.
In the `isEmpty` method, we check if the `top` variable is -1, which means the stack is empty.
In the `isFull` method, we check if the `top` variable is equal to `maxSize - 1`, which means the stack is full.
In the `Main` class, we create a new `Stack` object with a maximum size of 5. We then push some elements onto the stack, print the top element, push some more elements, and finally pop all the elements off the stack and print them.