Largest prime factor（最大素数因子）

Largest prime factor

Time Limit: 5000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 6106 Accepted Submission(s): 1876

Problem Description Everybody knows any number can be combined by the prime number. Now, your task is telling me what position of the largest prime factor. The position of prime 2 is 1, prime 3 is 2, and prime 5 is 3, etc. Specially, LPF(1) = 0.

Input Each line will contain one integer n(0 < n < 1000000).

Output Output the LPF(n).

Sample Input 1 2 3 4 5

Sample Output 0 1 2 1 3  给出一个数，求其最大质因数所在全体素数的第几位 #include int a[1000010],b[1000001]; int main() {a[0]=1; a[1]=1; int k=1; for(int i=2;i<1000010;i++) {if(a[i]==0) {b[i]=k++;//定位 for(int j=i;j<1000010;j=j+i) a[j]=i;//最大素数因子 } } b[1]=0; int n,sum; while(~scanf("%d",&n)) { printf("%d\n",b[a[n]]); } }