Solved ProjectEuler/018: php, ruby

ProjectEuler/018/desc.yml

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+title: Find the maximum sum travelling from the top of the triangle to the base.
+url: http://projecteuler.net/problem=18
+
+desc: |
+  By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total from top to bottom is 23.
+  3
+  7 4
+  2 4 6
+  8 5 9 3
+  That is, 3 + 7 + 4 + 9 = 23.
+  Find the maximum total from top to bottom of the triangle below
+  (See file input)
+
+  
+solution: Instead of bruteforcing from top to bottom simply add the numbers from the bottom up and let the "highest" number win in a shootout
+
+solutions:
+  solve.php:
+    desc: Basic solution
+    language: php
+  solve.rb:
+    desc: Basic solution
+    language: ruby

ProjectEuler/018/input

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+75
+95 64
+17 47 82
+18 35 87 10
+20 04 82 47 65
+19 01 23 75 03 34
+88 02 77 73 07 63 67
+99 65 04 28 06 16 70 92
+41 41 26 56 83 40 80 70 33
+41 48 72 33 47 32 37 16 94 29
+53 71 44 65 25 43 91 52 97 51 14
+70 11 33 28 77 73 17 78 39 68 17 57
+91 71 52 38 17 14 91 43 58 50 27 29 48
+63 66 04 68 89 53 67 30 73 16 69 87 40 31
+04 62 98 27 23 09 70 98 73 93 38 53 60 04 23

ProjectEuler/018/solve.php

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+<?php
+foreach(file('php://stdin') as $line) {
+$tri[] = explode(' ',trim($line));
+}
+for($y=count($tri);$y>=0;$y--) {
+
+	for($x=0;$x<count($tri[$y]);$x++) {
+	$cur = $tri[$y][$x];
+		if($cur + $tri[$y+1][$x] > $cur + $tri[$y+1][$x+1]) {
+			$tri[$y][$x] =  $cur + $tri[$y+1][$x];
+		} else {
+			$tri[$y][$x] = $cur + $tri[$y+1][$x+1];
+		}
+	}
+}
+echo $tri[0][0];

ProjectEuler/018/solve.rb

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+tri = []
+linenum = 0
+ARGF.lines("\n") do |line|
+	tri[linenum] = Array.new
+	line.split.each do |str|
+		tri[linenum] << str.to_i
+	end
+	linenum += 1
+end
+
+(0..13).reverse_each do |y|
+	0.upto(tri[y].size()-1) do |x|
+		if( tri[y+1][x] > tri[y+1][x+1]) 
+			tri[y][x] =  tri[y][x] + tri[y+1][x]
+		else
+			tri[y][x] = tri[y][x] + tri[y+1][x+1]
+		end
+	end
+end
+puts tri[0][0]