有關大數的相關用法，請參考
http://celinechiu0809.blogspot.tw/2015/04/c-big-numnbers.html
題目連結
題目大意
輸出階層，最大為1000!
解題思路
標準的大數題。這一題因為測資數*位數太過龐大，從頭算的話非常容易TLE，所以先開陣列存1!~1000!，後查表即可。
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| #include <cstdio>#include <cstdio>#include <cstdlib>#include <cmath>#define MAX_LENGTH 3000#define DIGIT 10int ans[1001][3000];using namespace std;void big_mul(int *num1, int num2, int *answer){ int carry=0; for(int i=0; i< MAX_LENGTH; i++) answer[i]=0; for(int i=0; i< MAX_LENGTH; i++){ int t = answer[i] + num1[i]*num2 + carry; answer[i] = t%10; carry = t/10; }}void big_fact(){ for (int i=0; i< 1001; i++) { for (int j=0; j< 3000; j++) { ans[i][j]=0; } } ans[0][0] = 1; ans[1][0] = 1; for (int i=2; i<=1000; i++) big_mul(ans[i-1], i, ans[i]);}int main(){ int n; big_fact(); while(scanf("%d", &n)!=EOF){ int flag=0; printf("%d!\n",n); for(int i=MAX_LENGTH-1; i>=0; i--){ if (flag==0 && ans[n][i]!=0) flag=1; if (flag==1) printf("%d", ans[n][i]); } printf("\n"); } return 0;} |
