2011-12-18 20:12:15Morris
[UVA] 136 - Ugly Numbers
Ugly Numbers
| Ugly Numbers |
Ugly numbers are numbers whose only prime factors are 2, 3 or 5. The sequence
1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, ...
shows the first 11 ugly numbers. By convention, 1 is included.
Write a program to find and print the 1500'th ugly number.
Input and Output
There is no input to this program. Output should consist of a single line as shown below, with <number> replaced by the number computed.
Sample output
The 1500'th ugly number is <number>.
#include<stdio.h>
int main() {
int DP[1500] = {1}, t2 = 0, t3 = 0, t5 = 0, tmp, i;
for(i = 1; i < 1500; i++) {
while(DP[t2]*2 <= DP[i-1]) t2++;
while(DP[t3]*3 <= DP[i-1]) t3++;
while(DP[t5]*5 <= DP[i-1]) t5++;
tmp = DP[t2]*2;
if(DP[t3]*3 < tmp) tmp = DP[t3]*3;
if(DP[t5]*5 < tmp) tmp = DP[t5]*5;
DP[i] = tmp;
}
printf("The 1500'th ugly number is %d.\n", DP[1499]);
return 0;
}