【ACM】Largest prime factor

/*打表把素数能组合的数先设置成相应的位数*/
/* if n equals two and n is No.1 position of prime factors  so four position of prime factors is no.1,as well*/
/* although two can combined six but three also can combined six */
/* and three position of prime factors is two ,two covered one then six largest prime factor */
/*position is two now, have fun ;-) */

#include <stdio.h>
#include <stdlib.h>
#define MAX 1000000
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
int main(int argc, char *argv[]) {
	int *lpf = malloc( MAX*sizeof(int) ); /*if use "int lpf[MAX]" could be overflow*/
	int n , num ;
	int i , j ;
	num = 0 ;
	lpf[1] = 0 ;
	for( i = 2 ; i < MAX ; i++ ) {
		if( 0 == lpf[i] ){
			num++ ;
		for( j = i ; j < MAX ; j=j+i )
			lpf[j] = num ;
		}

	}
	while( scanf("%d",&n) != EOF )
		printf("%d\n",lpf[n]);
	return 0;
}