华为机试练习

挑7_牛客题霸_牛客网

整数转换为字符串String numStr = String.valueOf(str);

String有一个contains方法，查看是否包含字符串

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int ans = 0;
        for(int i = 1;i <= n;i++)
        {
            if(check(i))
            {
                ans++;
            }
        }
        System.out.print(ans);
    }

    public static boolean check(int x){
        if(x % 7 == 0)
        {
            return true;
        }
        String s = String.valueOf(x);
        if(s.contains("7"))
        {
            return true;
        }
        return false;
    }
}

高精度整数加法_牛客题霸_牛客网

使用字符串处理即可

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String a = in.next();
        String b = in.next();
        int len1 = a.length();
        int len2 = b.length();
        int bigger = 0;
        if(len1 > len2)
        {
            bigger = 1;
        }
        else if(len1 < len2)
        {
            bigger = 2;
        }
        int i = a.length() - 1;
        int j = b.length() - 1;
        int judge = 0;//判断是否进位
        String ans = "";
        while(i >= 0 && j >= 0)
        {
            char c1 = a.charAt(i);
            char c2 = b.charAt(j);
            int n1 = c1 - '0';
            int n2 = c2 - '0';
            int cur = n1 + n2 + judge;
            if(cur >= 10)
            {
                judge = 1;
                cur -= 10;
            }
            else
            {
                judge = 0;
            }
            String numStr = String.valueOf(cur);
            ans = numStr + ans;
            i--;
            j--;
            if(i < 0 || j < 0)
            {
                break;
            }
        }
        //处理长度不一样的情况
        if(i < 0)
        {
            while(j >= 0)
            {
                char c = b.charAt(j);
                int cur = c - '0';
                cur += judge;
                if(cur >= 10)
                {
                    cur -= 10;
                    judge = 1;
                }
                else
                {
                    judge = 0;
                }
                String numStr = String.valueOf(cur);
                ans = numStr + ans;
                j--;
            }
        }
        if(j < 0)
        {
            while(i >= 0)
            {
                char c = a.charAt(i);
                int cur = c - '0';
                cur += judge;
                if(cur >= 10)
                {
                    cur -= 10;
                    judge = 1;
                }
                else
                {
                    judge = 0;
                }
                String numStr = String.valueOf(cur);
                ans = numStr + ans;
                i--;
            }
        }


        if(judge == 1)
        {
            ans = "1" + ans;
        }
        System.out.print(ans);
    }
}