1013.cpp

这是哈尔滨工业大学acmOJ的源代码

/*  This Code is Submitted by wywcgs for Problem 1013 on 2006-01-08 at 23:56:01 */ 
#include <cstdio>
#include <cstring>

const int MAX = 1024;

int f(char*, int);

int main()
{
	char digit[MAX];
	
	while(scanf("%s", digit) != EOF) {
		int i, l = strlen(digit), n = (l+1) / 2;
		for(i = 0; i < n; i++) {
			char t = digit[i] - '0';
			digit[i] = digit[l-i-1] - '0';
			digit[l-i-1] = t;
		}
		printf("%d\n", f(digit, l));
	}

	return 0;
}

int f(char* d, int l)
{
	int r = 1, i;
	switch(d[0]%5) {
	case 2: r = 2; break;
	case 3: r = 6; break;
	case 4: r = 4; break;
	}
	if(l == 1 && d[0] < 5) return r;
	else {
		for(i = 0; i < l; i++) {
			if(i != 0) d[i-1] += d[i]*10%50/5;
			d[i] /= 5;
		}
		if(d[l-1] == 0) l--;
		switch((d[1]*10+d[0])%4) {
		case 0: r *= 6; break;
		case 1: r *= 2; break;
		case 2: r *= 4; break;
		case 3: r *= 8; break;
		}
		return r*f(d, l)%10;
	}
}