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// 264. Ugly Number II
#include "leetcode.h"
/*
* an ugly number is a positive integer whose prime factors are limited to
* 2,3,5. given an integer 'n', return the n'th ugly number
*/
int nthUglyNumber(int n) {
int *ugly_nums = (int *)malloc(n * sizeof(int));
ugly_nums[0] = 1;
int idx2 = 0, idx3 = 0, idx5 = 2, f2 = 0, f3 = 3, f5 = 5;
for (int i = 1; i < n; i++) {
int tmp = f2 < f3 ? f2 : f3, min = tmp < f5 ? tmp : f5;
ugly_nums[i] = min;
if (min == f2)
f2 = 2 * ugly_nums[++idx2];
if (min == f3)
f3 = 3 * ugly_nums[++idx3];
if (min == f5)
f5 = 5 * ugly_nums[++idx5];
}
int ans = ugly_nums[n - 1];
free(ugly_nums);
return ans;
}
int main() {
printf("%d\n", nthUglyNumber(10)); // expect: 12
printf("%d\n", nthUglyNumber(1)); // expect: 1
}
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