Humble Numbers

1
2
3
4
11
12
13
21
22
23
100
1000
5842
0

The 1st humble number is 1.
The 2nd humble number is 2.
The 3rd humble number is 3.
The 4th humble number is 4.
The 11th humble number is 12.
The 12th humble number is 14.
The 13th humble number is 15.
The 21st humble number is 28.
The 22nd humble number is 30.
The 23rd humble number is 32.
The 100th humble number is 450.
The 1000th humble number is 385875.
The 5842nd humble number is 2000000000.

#include <stdio.h>
#define maxn 5845

int dp[maxn] = {1, 1};
int a, b, c, d;
const char *sam[] = { "st", "nd", "rd", "th" };

int min(int u, int v, int x, int y)
{
    int tmp = u;
    if(tmp > v) tmp = v;
    if(tmp > x) tmp = x;
    if(tmp > y) tmp = y;

    if(tmp == u) ++a;
    if(tmp == v) ++b;
    if(tmp == x) ++c;
    if(tmp == y) ++d;
    
    return tmp;
}

const char *f(int n)
{
    if(n % 10 == 1 && n % 100 != 11) return sam[0];
    if(n % 10 == 2 && n % 100 != 12) return sam[1];
    if(n % 10 == 3 && n % 100 != 13) return sam[2];
    return sam[3];
}

int main()
{
    int i, n;
    a = b = c = d = 1;
    for(i = 2; i < maxn; ++i)
        dp[i] = min(dp[a] * 2, dp[b] * 3, dp[c] * 5, dp[d] * 7);
    while(scanf("%d", &n), n)
        printf("The %d%s humble number is %d.\n", n, f(n), dp[n]);
    return 0;
}