每日算法3 —— UVa1225 数数字 Digit Counting , ACM/ICPC Danang 2007

一、Question

1. 题目描述

Trung is bored with his mathematics homeworks. He takes a piece of chalk and starts writing a sequence of consecutive integers starting with 1 to N (1 < N < 10000). After that, he counts the number of times each digit (0 to 9) appears in the sequence. For example, with N = 13, the sequence is:12345678910111213

In this sequence, 0 appears once, 1 appears 6 times, 2 appears 2 times, 3 appears 3 times, and each digit from 4 to 9 appears once. After playing for a while, Trung gets bored again. He now wants to write a program to do this for him. Your task is to help him with writing this program.
此题要求我们把前n(n≤10000)个整数顺次写在一起：123456789101112 ··· 数一数0~9个出现多少次（输出10个整数，分别是0，1，··· ，出现的次数）。

2. Input

The input file consists of several data sets. The first line of the input file contains the number of data sets which is a positive integer and is not bigger than 20. The following lines describe the data sets. For each test case, there is one single line containing the number N.

3. Output

For each test case, write sequentially in one line the number of digit 0,1,…9 separated by a space.

4. Sample Input

2
3
13

5. Sample Output

0 1 1 1 0 0 0 0 0 0
1 6 2 2 1 1 1 1 1 1

二、题解

1. C++

#include
using namespace std;
string NumberToString(int x)
{
    stringstream ss;
    ss << x;
    return ss.str();
}

int main()
{
    int n;
    scanf("%d", &n);
    while (n--)
    {
        int num;
        scanf("%d", &num);
        int a[10];
        memset(a, 0, sizeof (a));
        for(int i = 1; i <= num; ++i)
        {
            string s = NumberToString(i);
            int length = s.length();
            for(int j = 0; j < length; ++j)
            {
                int pos = int(s[j])-48;
                a[pos]++;
            }
        }
        for(int pp = 0; pp < 10; ++pp)
        {
            printf("%d", a[pp]);
        }
        printf("\n");
    }
}

2. Python

if __name__ == '__main__':
    n = int(input())
    for qq in range(n):
        num = int(input())
        a = [0] * 10
        for i in range(num):
            s = str(i+1)
            length = len(s)
            for j in range(length):
                pos = int(s[j])
                a[pos] = a[pos] + 1
        for k in range(10):
            print(a[k], end='')
        print('\n')