C语言常见算法——求大数阶乘！

注意点：

1 是大数的阶乘

2 注意会溢出

/************************************************************************* ??? > File Name: Factorial.c ??? > Author: hai--feng ??? > Mail: haifeng@126.com ??? > Created Time: Tue 26 Mar 2013 08:11:03 AM CST ?************************************************************************/ #include <stdio.h> void Factorial( int val ) { ??? int Data[ 10000 ] = { 0 }; ??? int media = 1;????????????? //有效数据个数 ??? int ii = 0,ij = 0; ??? if( 0 > val ) ??? { ??????? printf( "param is illegal!n" ); ??? } ??? else ??? { ??????? if( val == 0 )??? //0的阶乘为1 ??????? { ??????????? Data[ media - 1 ] = 1; ??????? } ??????? else ??????? { ??????????? for( ii = 1; ii <= val; ii++ )??? //循环val次 ??????????? { ??????????????? for( ij = 0; ij < media; ij++ )???? //每一次对于当前数据求阶乘 ??????????????? { ??????????????????? if( ( 1 == media ) && ( 1 == ii ) )?? //如果是1的阶乘 ??????????????????? { ??????????????????????? Data[ ij ] = 1; ??????????????????? } ??????????????????? else ??????????????????? { ??????????????????????? Data[ ij ] *= ii;??? //求每一个单元的值 ??????????????????? } ??????????????? } ??????????????? for( ij = 0; ij < media; ij++ )??????? //进位 ??????????????? { ??????????????????? if( ( ij < ( media -1 ) ) && ( Data[ ij ] >= 10 ) )?????? //如果在当前的有效数据范围内部 ??????????????????? { ??????????????????????? Data[ ij + 1 ] += Data[ ij ] / 10; ??????????????????????? Data[ ij ] %= 10; ??????????????????? } ??????????????????? else if( ( ij == ( media -1 ) ) && ( Data[ ij ] >= 10 ) )???? //如果在当前的有效数据范围外部，有效数据个数++ ??????????????????? { ??????????????????????? Data[ media ] += Data[ ij ] / 10; ??????????????????????? Data[ ij ] %= 10; ??????????????????????? media++; ??????????????????? } ??????????????? } ??????????? } ??????? } ??????? for( ii = ( media - 1 ); ii >= 0; ii-- ) ??????? { ??????????? printf( "%2d",Data[ ii ] ); ??????? } ??????? printf( "n" ); ??? } } int main(void) { ??? int factorial = 0; ??? while( 1 ) ??? { ??????? printf( "enter number:" ); ??????? scanf( "%d",&factorial ); ??????? Factorial( factorial ); ??? } ?? ? ??? return 0; } 思想：? 如n！，循环次数为n，对于每一次循环，对应位算出结果，然后算出对于10的余数，其商进位。