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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="problem">Problem<a href="#problem" class="hash-link" aria-label="Direct link to Problem" title="Direct link to Problem"></a></h2>
<p>The problem we are going to solve is one of <em>CodeWars</em> katas and is called
<a href="https://www.codewars.com/kata/551f23362ff852e2ab000037" target="_blank" rel="noopener noreferrer">Pyramid Slide Down</a>.</p>
<p>We are given a 2D array of integers and we are to find the <em>slide down</em>.
<em>Slide down</em> is a maximum sum of consecutive numbers from the top to the bottom.</p>
<p>Let&#x27;s have a look at few examples. Consider the following pyramid:</p>
<div class="codeBlockContainer_Ckt0 theme-code-block" style="--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-text codeBlock_bY9V thin-scrollbar" style="background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 3</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 7 4</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 2 4 6</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain">8 5 9 3</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div>
<p>This pyramid has following slide down:</p>
<div class="codeBlockContainer_Ckt0 theme-code-block" style="--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-text codeBlock_bY9V thin-scrollbar" style="background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> *3</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> *7 4</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 2 *4 6</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain">8 5 *9 3</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div>
<p>And its value is <code>23</code>.</p>
<p>We can also have a look at a <em>bigger</em> example:</p>
<div class="codeBlockContainer_Ckt0 theme-code-block" style="--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-text codeBlock_bY9V thin-scrollbar" style="background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 75</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 95 64</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 17 47 82</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 18 35 87 10</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 20 4 82 47 65</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 19 1 23 3 34</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 88 2 77 73 7 63 67</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 99 65 4 28 6 16 70 92</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 41 41 26 56 83 40 80 70 33</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 41 48 72 33 47 32 37 16 94 29</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 53 71 44 65 25 43 91 52 97 51 14</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 70 11 33 28 77 73 17 78 39 68 17 57</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 91 71 52 38 17 14 91 43 58 50 27 29 48</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 63 66 4 68 89 53 67 30 73 16 69 87 40 31</span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> 4 62 98 27 23 9 70 98 73 93 38 53 60 4 23</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div>
<p>Slide down in this case is equal to <code>1074</code>.</p>
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="solving-the-problem">Solving the problem<a href="#solving-the-problem" class="hash-link" aria-label="Direct link to Solving the problem" title="Direct link to Solving the problem"></a></h2>
<div class="theme-admonition theme-admonition-warning admonition_xJq3 alert alert--warning"><div class="admonitionHeading_Gvgb"><span class="admonitionIcon_Rf37"><svg viewBox="0 0 16 16"><path fill-rule="evenodd" d="M8.893 1.5c-.183-.31-.52-.5-.887-.5s-.703.19-.886.5L.138 13.499a.98.98 0 0 0 0 1.001c.193.31.53.501.886.501h13.964c.367 0 .704-.19.877-.5a1.03 1.03 0 0 0 .01-1.002L8.893 1.5zm.133 11.497H6.987v-2.003h2.039v2.003zm0-3.004H6.987V5.987h2.039v4.006z"></path></svg></span>caution</div><div class="admonitionContent_BuS1"><p>I will describe the following ways you can approach this problem and implement
them in <em>Java</em><sup><a href="#user-content-fn-1" id="user-content-fnref-1" data-footnote-ref="true" aria-describedby="footnote-label">1</a></sup>.</p></div></div>
<p>For all of the following solutions I will be using basic <code>main</code> function that
will output <code>true</code>/<code>false</code> based on the expected output of our algorithm. Any
other differences will lie only in the solutions of the problem. You can see the
<code>main</code> here:</p>
<div class="language-java codeBlockContainer_Ckt0 theme-code-block" style="--prism-background-color:hsl(230, 1%, 98%);--prism-color:hsl(230, 8%, 24%)"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-java codeBlock_bY9V thin-scrollbar" style="background-color:hsl(230, 1%, 98%);color:hsl(230, 8%, 24%)"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token keyword" style="color:hsl(301, 63%, 40%)">public</span><span class="token plain"> </span><span class="token keyword" style="color:hsl(301, 63%, 40%)">static</span><span class="token plain"> </span><span class="token keyword" style="color:hsl(301, 63%, 40%)">void</span><span class="token plain"> </span><span class="token function" style="color:hsl(221, 87%, 60%)">main</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token class-name" style="color:hsl(35, 99%, 36%)">String</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">[</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">]</span><span class="token plain"> args</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">System</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">.</span><span class="token plain">out</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">.</span><span class="token function" style="color:hsl(221, 87%, 60%)">print</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token string" style="color:hsl(119, 34%, 47%)">&quot;Test #1: &quot;</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">)</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> </span><span class="token class-name" style="color:hsl(35, 99%, 36%)">System</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">.</span><span class="token plain">out</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">.</span><span class="token function" style="color:hsl(221, 87%, 60%)">println</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token function" style="color:hsl(221, 87%, 60%)">longestSlideDown</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">(</span><span class="token keyword" style="color:hsl(301, 63%, 40%)">new</span><span class="token plain"> </span><span class="token keyword" style="color:hsl(301, 63%, 40%)">int</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">[</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">]</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">[</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">]</span><span class="token plain"> </span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> </span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">{</span><span class="token plain"> </span><span class="token number" style="color:hsl(35, 99%, 36%)">3</span><span class="token plain"> </span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">}</span><span class="token punctuation" style="color:hsl(119, 34%, 47%)">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:hsl(230, 8%, 24%)"><span class="token plain"> </span><span class="token punctuation" style="color:hsl(119, 34%, 47
<section data-footnotes="true" class="footnotes"><h2 class="anchor anchorWithStickyNavbar_LWe7 sr-only" id="footnote-label">Footnotes<a href="#footnote-label" class="hash-link" aria-label="Direct link to Footnotes" title="Direct link to Footnotes"></a></h2>
<ol>
<li id="user-content-fn-1">
<p>cause why not, right!? <a href="#user-content-fnref-1" data-footnote-backref="" aria-label="Back to reference 1" class="data-footnote-backref"></a></p>
</li>
</ol>
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