字符串的反转

/**
 * 双指针的简单思路解法
 * @param s
 * @return
 */
public String reverserString1(String s){
    //将字符串 s 变成 字符数组
    char[] c = s.toCharArray();
    //定义左右指针
    int left = 0;
    int right = c.length - 1;
    while(left <= right){
        //进行左右两端的字符交换
        char tempC = c[left];
        c[left] = c[right];
        c[right] = tempC;
        left ++;
        right --;
    }
    return new String(c);
}

/**
 * 借助栈的特性，先进后出
 * @param s
 * @return
 */
public String reverserString2(String s){
    LinkedList<Character> stack = new LinkedList<>();
    char[] c = s.toCharArray();
    for(char c1 : c){
        stack.push(c1);
    }
    //定义字符拼接对象 StringBuilder
    StringBuilder sb = new StringBuilder();
    //只要stack不空，我们就弹出栈顶元素
    while(!stack.isEmpty()){
        sb.append(stack.pop());
    }
    return sb.toString();
}

/**
 * 借助原生的StringBuilder进行翻转操作
 * @param s
 * @return
 */
public String reverserString3(String s){
    StringBuilder sb = new StringBuilder(s);
    sb.reverse();
    return sb.toString();
}