easy Python code for 668. Kth Smallest Number in Multiplication Table, and **beats 100% with 488ms runtime**.

Based on https://leetcode.com/problems/kth-smallest-number-in-multiplication-table/discuss/, 5.solution like Kth Smallest Number in Sorted Matrix, I just improve it by **asserting m <= n**.

class Solution(object): def findKthNumber(self, m, n, k): """ :type m: int :type n: int :type k: int :rtype: int """ def countLessThan(x, m, n): assert m <= n count = 0 for i in xrange(1, m+1): if x/i < n: count += x/i else: count += n return count if m > n: m, n = n, m lo, hi = 1, m*n while lo < hi: mid = (lo + hi)/2 if countLessThan(mid, m, n) < k: lo = mid + 1 else: hi = mid return lo