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POThe Skyline Problem‍
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copied!<p>I just came across this little problem on <a href="http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=3&page=show_problem&problem=41" rel="nofollow noreferrer">UVA's Online Judge</a> and thought, that it may be a good candidate for a little code-golf.</p> <p><strong>The problem:</strong></p> <p>You are to design a program to assist an architect in drawing the skyline of a city given the locations of the buildings in the city. To make the problem tractable, all buildings are rectangular in shape and they share a common bottom (the city they are built in is very flat). The city is also viewed as two-dimensional. A building is specified by an ordered triple <strong>(Li, Hi, Ri)</strong> where <strong>Li</strong> and <strong>Ri</strong> are left and right coordinates, respectively, of building i and <strong>Hi</strong> is the height of the building. </p> <p><img src="https://imgur.com/SnSjn.gif" alt="alt text"></p> <p>In the diagram below buildings are shown on the left with triples </p> <pre><code>(1,11,5), (2,6,7), (3,13,9), (12,7,16), (14,3,25), (19,18,22), (23,13,29), (24,4,28) </code></pre> <p>and the skyline, shown on the right, is represented by the sequence: </p> <pre><code>1, 11, 3, 13, 9, 0, 12, 7, 16, 3, 19, 18, 22, 3, 23, 13, 29, 0 </code></pre> <p>The output should consist of the vector that describes the skyline as shown in the example above. In the skyline vector <strong>(v1, v2, v3, ... vn)</strong> , the <strong>vi</strong> such that i is an even number represent a horizontal line (height). The <strong>vi</strong> such that i is an odd number represent a vertical line (x-coordinate). The skyline vector should represent the "path" taken, for example, by a bug starting at the minimum x-coordinate and traveling horizontally and vertically over all the lines that define the skyline. Thus the last entry in the skyline vector will be a 0. The coordinates must be separated by a blank space.</p> <p>If I will not count declaration of provided (test) buildings and including all spaces and tab characters, my solution, in Python, is <strong>223</strong> characters long.</p> <p>Here is the condensed version:</p> <pre><code>B=[[1,11,5],[2,6,7],[3,13,9],[12,7,16],[14,3,25],[19,18,22],[23,13,29],[24,4,28]] # Solution. R=range v=[0 for e in R(max([y[2] for y in B])+1)] for b in B: for x in R(b[0], b[2]): if b[1]>v[x]: v[x]=b[1] p=1 k=0 for x in R(len(v)): V=v[x] if p and V==0: continue elif V!=k: p=0 print "%s %s" % (str(x), str(V)), k=V </code></pre> <p>I think that I didn't made any mistake but if so - feel free to criticize me.</p> <p>I don't have much reputation, so I will pay only 100 for a bounty - I am curious, if anyone could try to solve this in less than .. lets say, 80 characters. Solution posted by <strong>cobbal</strong> is <a href="https://stackoverflow.com/questions/1066234/the-skyline-problem/1073337#1073337">101 characters long</a> and currently it is the best one.</p> <p>I thought, that 80 characters is a sick limit for this kind of problem. <strong>cobbal</strong>, with his 46 character solution totaly amazed me - though I must admit, that I spent some time reading his explanation before I partially understood what he had written.</p>

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