算法学习-day01

1：给你一串数字，比如1234567890，变成1,234,567,890（字符串形式）

import java.util.Stack;
​
public class Answer {
​
    public static void main(String[] args) {
        String a = "112348554";
        Stack stck = new Stack();
        for (int i = a.length()-1; i>=0; i--) {
            stck.add(a.charAt(i));
            if(i % 3 == 0 && i >0) {
                stck.add(",");
            }
        }
        StringBuffer sb = new StringBuffer();
        while(!stck.empty()) {
            sb.append(stck.pop());
        }
        System.out.println(sb.toString());
    }
}

2：给你一串字符串数字，把他变成整型的数字，比如：‘1234123’ 转变为 1234123，不能使用工具类

public class Answer {
    public static void main(String[] args) {
        String a = "3322";
        int record = 0;
        for (int i = 0; i < a.length(); i++) {
            char temp = a.charAt(i);
            int diff = temp - '0';
            record = diff + record*10;
        }
        System.out.println(record);
    }
}