Solved ProjectEuler/039,041,042

ProjectEuler/039/desc.yml

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+title: Integer right triangles
+url: http://projecteuler.net/problem=39
+
+desc: |
+    If p is the perimeter of a right angle triangle with integral length sides, {a,b,c}, there are exactly three solutions for p = 120.
+    {20,48,52}, {24,45,51}, {30,40,50}
+    For which value of p <=1000, is the number of solutions maximised?
+      
+solution: |
+  Bruteforce
+
+solutions:
+  solve.php:
+    desc: Basic solution
+    language: php
+  solve.c:
+    desc: Basic solution
+    language: c

ProjectEuler/039/solve.c

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+#include <stdio.h>
+#define P_VALUE 1000
+
+int p, a, b, c, max, key, result = 0;
+int main( )
+{
+	for(p=2;p<P_VALUE;p++)
+	{
+
+		for(a=2;a<p;a++)
+		{
+			for(b=a;b<p;b++)
+			{
+				//Find C so it runs faster...
+				c = p - a - b;
+					if(a*a+b*b == c*c) {
+						result++;
+					}
+			}
+		}
+		if(result > max) {
+			max = result;
+			key = p;
+		}
+		result = 0;
+	}
+	printf( "%i", key);
+}

ProjectEuler/039/solve.php

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+<?php
+define('P_VALUE',1000);
+
+for($p=2;$p<P_VALUE;$p++) {
+
+	for($a=2;$a<$p;$a++) {
+		for($b=$a;$b<$p;$b++) {
+			//Find C so it runs faster...
+			$c = $p - $a - $b;
+			if($a*$a+$b*$b == $c*$c) {
+				$result++;
+			}
+		}
+	}
+	if($result > $max) {
+		$max = $result; $key = $p;
+	}
+	$result = 0;
+}
+echo $key;

ProjectEuler/041/desc.yml

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+title: Integer right triangles
+url: http://projecteuler.net/problem=41
+
+desc: |
+    We shall say that an n-digit number is pandigital if it makes use of all the digits 1 to n exactly once. For example, 2143 is a 4-digit pandigital and is also prime.
+    What is the largest n-digit pandigital prime that exists?
+      
+solution: |
+  Bruteforce
+
+solutions:
+  solve.php:
+    desc: Basic solution
+    language: php

ProjectEuler/041/solve.php

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+<?php
+
+function pandigital_less($number) {
+
+		$array = count_chars($number,1);
+		
+		foreach(range(1,count($array)) as $char) {
+			if( $array[ord($char)]!== 1) return false;
+		}
+		return true;
+}
+
+function is_prime($prime) {
+    //if($prime%2 == 0) return false;
+    
+    $sqrt = sqrt($prime);
+    for ($i = 3; $i <= $sqrt; $i+=2){
+        if ($prime%$i == 0) return false; 
+    } 
+    return true; 
+} 
+//We don't need to check uneven numbers
+//Has to start with a 7 and therefor be 7 digits long
+for($var = 7000001; $var < 8000000; $var=$var+2) { 
+	if(is_prime($var) AND pandigital_less($var)) { $result =  $var; }
+}
+echo $result;

ProjectEuler/042/desc.yml

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+title: Coded triangle numbers
+url: http://projecteuler.net/problem=42
+
+desc: |
+    The nth term of the sequence of triangle numbers is given by, tn = 0.5n(n+1); so the first ten triangle numbers are:
+    1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
+    By converting each letter in a word to a number corresponding to its alphabetical position and adding these values we form a word value. For example, the word value for SKY is 19 + 11 + 25 = 55 = t10. If the word value is a triangle number then we shall call the word a triangle word.
+    Using words.txt (right click and 'Save Link/Target As...'), a 16K text file containing nearly two-thousand common English words, how many are triangle words?
+solution: Bruteforce
+
+solutions:
+  solve.php:
+    desc: Expects data on STDIN
+    language: php
+    parameters: < ProjectEuler\042\words.txt

ProjectEuler/042/solve.php

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+<?php
+$words = explode('","',substr(file_get_contents('php://STDIN'),1,-1));
+
+//Find triangles
+for($t=1;$t<40;$t++) {
+	$triangle_numbers[] = 0.5*$t*($t+1);
+}
+
+foreach($words as $word) {
+	for($c =0; $c < strlen($word); $c++) {
+		$char_sum += ord($word[$c]) - 64;	
+	}
+	if(in_array($char_sum,$triangle_numbers)) {
+		$result++;
+	}
+	$char_sum = 0;
+}
+echo $result;