monte carlo birthday problem java

1#include <stdio.h>        // print
2#include <stdlib.h>   <span                data-mce-type="bookmark"                id="mce_SELREST_start"              data-mce-style="overflow:hidden;line-height:0"              style="overflow:hidden;line-height:0"           ></span>   // rand
3#include <time.h>     // time
4 
5// This program will determine the percentage of times that two or more people share a birthday
6// It will iterate from 2 people to 'maxNumPeople' and in each version it will do 'numSimulations' simulations
7int main()
8{
9    int numPeople;                  // Number of people in this version
10    int maxNumPeople = 100;         // Maximum number of people to test with. Must be less than 100
11    int simNum;                     // Simulation number
12    long numSimulations = 1000000;  // Number of simulations to try in this version
13    long numMatches;                // Keeps track of number of matches in this version
14    int birthdays[100];
15    int i, j;                       // Incrementers fin for loop
16    int isMatch;                    // Flag for later
17 
18    // Seed RNG with time to get unique results each time
19    srand(time(NULL));
20 
21    // Iterate over the number of people in this version
22    for(numPeople=2; numPeople<maxNumPeople; numPeople++)
23    {
24        // Reset the number of matchs for this version
25        numMatches = 0;
26 
27        // Iterate the number of simulations in this version
28        for(simNum = 0; simNum<numSimulations; simNum++)
29        {
30            for(i=0; i<numPeople; i++)
31            {
32                // Give each bday a value, in this case a day from 1 to 365 inclusive
33                // rand()%365 returns from 0 to 364 so we add 1 to it
34                // We could just as easily leave the 1 off and it would still work, but doesn't hurt
35                birthdays[i] = 1 + rand()%365;
36            }
37 
38            // Reset the isMatch flag
39            isMatch=0; 
40 
41            // Determine if there is a match
42            // Note that this is a very inefficent way to do compare
43            for(i=0; i<numPeople-1; i++)
44            {
45                for(j=i+1; j<span                data-mce-type="bookmark"                id="mce_SELREST_start"              data-mce-style="overflow:hidden;line-height:0"              style="overflow:hidden;line-height:0"           ></span><numPeople; j++)
46                {
47                    // Compare i and j birthdays
48                    if(birthdays[i] == birthdays[j])
49                    {
50                        // If they match, then set flag and break
51                        isMatch=1;
52                        break;
53                    }
54                }
55 
56                // This flag is to break out of the outer for loop if a mathc is already found
57                if(isMatch==1)
58                {
59                    break;
60                }
61            }
62 
63            // If the match flag was set, increment the number of matches
64            if(isMatch==1)
65                numMatches++;
66 
67        }
68 
69        // Print out the numPeople in this version and the percentage of times there wa a match
70        printf("%d, %f \n", numPeople, 100.0*numMatches/numSimulations);
71    }
72 
73    return 0;
74}
75