Lightoj 1104-birthday Paradox "probability"

Title Link: http://www.lightoj.com/volume_showproblem.php?problem=1104
Test instructions: Birthday refutation, ask for the minimum number of people to meet the conditions
Code:

#include <stdio.h>#include <iostream>#include <string.h>#include <algorithm>#include <bitset>#include <math.h>#include <ctype.h>#include <time.h>#include <queue>#include <map>#include <set>using namespace STD;intTintNintdp[100010];intMain () {Cin>> T; for(intCA =1; CA <= T; ca++) {memset(DP,0,sizeof(DP));Cin>> N;cout<<"Case"<< CA <<": ";if(n = =1)cout<<1<< Endl;Else{DoubleAns =1.0;intI for(i =1; I <= N; i++) {ans *= (n-i) *1.0/n);if(Ans <=0.5) Break; }cout<< i << Endl; }    }return 0;}

Lightoj 1104-birthday Paradox "probability"