UVa 11971 (probability) Polygon

Test instructions

There is a rope, the above randomly selected K tangent point, cut it into k+1 section, to find the probability of these segments can be k+1 edge shape.

Analysis:

To form a k+1 edge, the longest segment must be smaller than the sum of the other K segments.

Purple Book gives a solution, but feel not too good to understand, so went to the Internet to find other solutions.

The question has been asked, and a number of rigorous solutions have been given.

The final code will be (1LL << i) written in (1 << i), this detail should be noted.

1#include <cstdio>2typedefLong Longll;3 4 ll GCD (ll A, ll b)5 {6     if(b = =0)returnA;7     returnGCD (b, a%b);8 }9 Ten Const intMAXN = -; Onell A[MAXN +5], B[MAXN +5]; A  - voidinit_table () - { theb[1] =1; -      for(inti =2; I <= MAXN; ++i) -     { - ll G; +B[i] = 1ll <<i; -A[i] = b[i]-I-1; +g =gcd (A[i], b[i]); AA[i]/= G, B[i]/=G; at     } - } -  - intMain () - { - init_table (); in     intT; -scanf"%d", &t); to      for(intKase =1; Kase <= t; ++Kase) +     { -         intK; thescanf"%d", &k); *scanf"%d", &k); $printf"Case #%d:%lld/%lld\n", Kase, A[k], b[k]);Panax Notoginseng     } -  the     return 0; +}

code June

UVa 11971 (probability) Polygon