729. Last Digit By Factorial Divide

Description

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We are given two numbers A and B such that B >= A. We need to compute the last digit of this resulting F such that F = B! / A! where 1 <= A, B <= 10^18 (A and B are very large)

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Example

Given A = 2, B = 4, return 2
A! = 2 and B! = 24, F = 24 / 2 = 12 --> last digit = 2

Given A = 107, B = 109, return 2

只看个位数就好了。有意思

int computeLastDigit(long long A, long long B) { // write your code here int res = 1; for(long long i = A + 1; i <= B; i++){ res *= (i % 10); res %= 10; if(res == 0){ return 0; } } return res; }