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Diffstat (limited to 'ugly_number2.c')
-rw-r--r-- | ugly_number2.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/ugly_number2.c b/ugly_number2.c new file mode 100644 index 0000000..194514b --- /dev/null +++ b/ugly_number2.c @@ -0,0 +1,31 @@ +// 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 +} |