Math: Odds of Blogs Sidebar Being Diagonal

2/5 * 1/4 * 1/3 * 1/2 = 2/120 = 1/60.

#!/usr/bin/perl -w
require LWP::UserAgent;
my $net = LWP::UserAgent->new;
$net->agent("Mozilla");
$url="http://www.teamliquid.net/forum/index.php?viewdays=30&show_part=18&currentpage=";
for($i=34;$i>=1;$i--) {
$_=$net->get("$url"."$i");
$_=$_->content;
while(s/href="\/blogs[^>]+>([^<]+)<[^\n]+\n<td [^>]+>([^<]+)<//) {
$lengths[length($2)]++;
}
}
for($i=1;$i<20;$i++) {
print $i.": ".$lengths[$i]."\n";
}

1: 0
2: 13
3: 28
4: 68
5: 103
6: 188
7: 131
8: 179
9: 115
10: 121
11: 77
12: 64
13: 46
14: 28
15: 25
16: 4
17: 0
18: 0
19: 0

#include<iostream>
#include "stdint.h"
using namespace std;
int64_t counts[] = {13,28,68,103,188,131,179,115,121,77,64,46,28,25,4};
int64_t ways[5][15];

int64_t num_of_ways(int pos, int num) {
if(pos==0) return counts[num];
if(ways[pos][num]>=0) return ways[pos][num];
int64_t sum=0;
for(int i=0;i<num;i++) sum+=num_of_ways(pos-1,i);
sum*=counts[num];
ways[pos][num] = sum;
return sum;
}

int main() {
for(int i=0;i<5;i++) for(int j=0;j<15;j++) {
ways[i][j]=-1;
}
int64_t ans=0;
for(int i=0;i<15;i++) {
ans+=num_of_ways(4,i);
}
cout<<ans<<endl;

}

I have no idea if this is correct, but I just wasted 20 minutes of my life doing this.

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