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N!

2013年02月16日 ⁄ 综合 ⁄ 共 1352字 ⁄ 字号小中大 ⁄ 评论关闭

Problem Description

Given an integer N(0 ≤ N ≤ 10000), your task is to calculate N!

Input

One N in one line, process to the end of file.

Output

For each N, output N! in one line.

Sample Input

1
2
3

Sample Output

1
2
6

Author

JGShining（极光炫影）

分析：要注意时间限制，特别当位数很大时，要进行的乘法操作也会很大！解决方法是每三位进行一次乘法操作！

参考答案：

#include <iostream> 
#include <cmath> 
#include <string> 
using namespace std;
void init(char v[]) 
{ 
	memset(v, 0, sizeof(v)); 
	v[0] = '1'; 
}
void multi(char v[], int mul) 
{ 
	int val, wadd, j; 
	wadd = 0; 
	for (j = 0; j < strlen(v); ++j) 
	{ 
		if (v[j]=='0'&&wadd == 0) 
			continue; 
		val = (v[j]-'0')*mul+wadd; 
		wadd = val/10; 
		v[j] = val%10+'0'; 
	} 
	while (wadd != 0) 
	{ 
		val = wadd%10; 
		wadd = wadd/10; 
		v[j++] = val+'0'; 
	} 
	v[j++] = '/0'; 
}
void multiQurick(char v[], int mul) 
{ 
	int val, wadd = 0, j; 
	int l = strlen(v), sub;
	for (j = 0; j <= l-1; ++j) 
	{ 
		sub = l-1-j; 
		if (sub == 0) 
		{ 
			val = (v[j]-'0'); 
			val = val*mul+ wadd; 
			v[j] = val%10+'0'; 
			wadd = val/10; 
		} 
		else if (sub == 1) 
		{ 
			val = (v[j]-'0')+ (v[j+1]-'0')*10; 
			val = val*mul+ wadd; 
			v[j] = val%10+'0'; 
			val = val/10; 
			v[++j] = val%10+'0'; 
			wadd = val/10; 
		} 
		else 
		{ 
			val = (v[j]-'0')+ (v[j+1]-'0')*10 +(v[j+2]-'0')*100; 
			val = val*mul+ wadd; 
			v[j] = val%10+'0'; 
			val = val/10; 
			v[++j] = val%10+'0'; 
			val = val/10; 
			v[++j] = val%10+'0'; 
			wadd = val/10; 
		} 
	} 
	while (wadd != 0) 
	{ 
		val = wadd%10; 
		wadd = wadd/10; 
		v[j++] = val+'0'; 
	} 
	v[j++] = '/0'; 
}
void revert(char v[]) 
{ 
	int l = strlen(v), i; 
	char tmp;
	for (i = 0; i < l/2; ++i) 
	{ 
		tmp = v[i]; 
		v[i] = v[l-i-1]; 
		v[l-i-1] = tmp; 
	} 
}
int main() 
{ 
	int n, i; 
	char res[100000];
	while(cin>>n) 
	{ 
		init(res); 
		for (i = 1; i <= n; ++i) 
		{ 
			multiQurick(res, i); 
		}
		revert(res); 
		cout<<res<<endl; 
	} 
	return 0; 
}

【上篇】又见c#
【下篇】VML实现的饼图JavaScript类封装

作者: fortified

该日志由 fortified 于11年前发表在综合分类下，最后更新于 2013年02月16日.
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