Lightoj 1234 Harmonic Number

Main topic:

Give a number n, find out 1/1+1/2+1/3+....+1/(n-1) +1/n; 1<=n<=100000000.

Problem Solving Ideas:

Because the value range of n is too large, marking the words will be super memory, so simply calculate the size of the memory, you can hit a save n=40,80,120 The table,

So, for the worst case of N, which is looping 39 times,

Code:

1#include <cmath>2#include <cstdio>3#include <cstring>4#include <iostream>5#include <algorithm>6 using namespacestd;7 8 #defineMAXN 25000059 #defineN 100000005Ten DoubleA[MAXN]; One  A intMain () - { -     intT, N, M, I, j, L =1; the     Doublenum =0; -      for(i=j=1; i<n; i++) -     { -num + =1.0/i; +         ifI +==0) -A[j++] =num; +     } Ascanf ("%d", &n); at      while(N--) -     { -  -scanf ("%d", &m); -         if(M = =1) -printf ("Case %d:1\n", l++); in         Else if(M = =2) -printf ("Case %d:1.5\n", l++); to         Else if(M = =6) +printf ("Case %d:2.450\n", l++); -         Else the         { *num = a[m/ +]; $             ints = m-m% +;Panax Notoginsengm = m% +; -              while(M--) the             { +S + +; Anum + =1.0/s; the             } +printf ("Case %d:%.10f\n", l++, num); -         } $     } $     return 0; -}

　　

Lightoj 1234 Harmonic Number