PAT甲级练习1001

1001. A+B Format (20)

首先来分析题目，这题

输入：输入两个整数，a和b，a和b取值范围[-10^7, 10^7]

输出：按格式输出a和b两数的和

因为之前做乙级被整数取值范围坑了，所以代码使用了long long int，但实际上这一题使用int就足够。

前面加那么多头文件只是因为懒。

# define _CRT_SECURE_NO_WARNINGS

# include <iostream>
# include <string>
# include <sstream>
# include <vector>
# include <algorithm>
# include <functional>
# include <iomanip>
# include <ctime>
# include <map>
# include <math.h>
# include <string.h>

using namespace std;

int main(void)
{
    long long int a, b;
    long long int t;
    string out;
    char c;
    cin >> a >> b;

    a = a + b;
    bool check = false;
    if (a < 0)                    //小于0的情况，后续补'-'
        check = true;
    else if (a == 0)            //等于0的情况，输出字符串out不会获得字符
    {
        cout << 0 << endl;
        return 0;
    }
    int flag = 0;
    while (a != 0)                //大于0的情况，逐个取位
    {
        t = a % 10;
        a = a / 10;
        if (t < 0)
            t = -t;                //负数情况，转换绝对值
        flag++;
        c = (int)t + '0';
        out = c + out;
        if (flag == 3 && a != 0)
        {
            out = ',' + out;    //每3个数补充','，且这个','前面还会有数字
            flag = 0;
        }
    }
    if (check)
        out = '-' + out;

    cout << out << endl;

    return 0;
}