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How to improve Algorithmic Programming Solving skill? [closed]

- by gaurav

Possible Duplicate: How can I improve my problem-solving ability? How do you improve your problem solving skills? Should I learn design patterns or algorithms to improve my logical thinking skills? What to do when you're faced with a problem that you can't solve quickly? Are there non-programming related activities akin to solving programming problems? I am a computer engineering graduate. I have studied programming since three years. I am good in coding and programming. I have been trying to compete in algorithmic competitions on sites such as topcoder,spoj since one and a half year, but I am still unable to solve problems other than too easy problems. I have learned from people that it takes practice to solve such problems. I try to solve those problems but sometimes I am unable to understand and even if I do understand I am unable to think of a good algorithm for solving it. Even if I solve I get Wrong answer and I am unable to figure out what is the problem with my code as it works on samples given on the sites but fails on test cases which they do not provide. I really want to solve those problems and become good in algorithms. I have read books for learning algorithms like Introduction to algorithms by CLRS,practicing programming questions. I have gone through some questions but they don't answer this question. I have seen the questions which are said duplicates but those questions focus on overall programming, but I am asking for algorithm related programming, basically for competing in programming which involve solving a problem statement then online judge will automatically evaluate it, such type of programming is quite different from the type of programming these questions discuss.

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I can write code...but can't design well. Any suggestions?

- by user396089

I feel that I am good at writing code in bits and pieces, but my designs really suck. The question is how do I improve my designs (in order to become a better designer). I think schools and colleges do a good job of teaching people as to how to become good at mathematical problem solving, but lets admit the fact that most programs taught at school are generally around 1000 - 2000 lines long, which means that it is mostly an academic exercise and no way reflects the complexity of real world software (a few hundred thousand to millions of lines of code). This is where I believe that even projects like topcoder/project euler also won't be of much help, they might sharpen your mathematical problem solving ability - but you might become a theoretician programmer; someone who is more interested in the nice, clean stuff, and someone who is utterly un-interested in the day to day mundane and hairy stuff that most application programmers deal with. So my question is how do I improve my design skills? That is the ability to design small/medium scale applications that will go into a few thousand of lines of code? How can I learn design skills that would help me build a better html editor kit, or some graphics program like gimp?

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Algorithm and data structure learning resources for dynamic programming

- by Pranav

Im learning dynamic programming now, and while I know the theory well, designing DP algorithms for new problems is still difficult. This is what i would really like now- A book or a website, which poses a problem which can be solved by dynamic programming. Also there is the solution with an explanation available, which i would like to see if i cant solve the problem even after butting my head at it for a few hours. Is there some resource that provides this sort of a thing for several categories of algorithms- like graph algorithms, dynamic programming, etc? P.S. I considered Topcoder, but the solutions there are not really appropriate for learning to implement efficient solutions.

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LaTex: why partially showing up references?

- by HH

The bib.style part may be the problem. If I do not reference to references, do they show up? I have listed all errors below, the file compiles so I don't know whether they are related to partially-showing-up-references. For example, work with many authors gets only one author listed. I want to see references fully, not partially. Headers $ grep bib header.tex \usepackage{natbib} \bibliographystyle{abbrvnat} Errors $ grep -n -A 7 -B 7 Error *.log combined.log-505-! Illegal unit of measure (pt inserted). combined.log-506-<to be read again> combined.log-507- \futurelet combined.log-508-l.353 \hline combined.log-509- combined.log-510-? combined.log-511- combined.log:512:! Package caption Error: cite undefined. combined.log-513- combined.log-514-See the caption package documentation for explanation. combined.log-515-Type H <return> for immediate help. combined.log-516- ... combined.log-517- combined.log-518-l.374 ...n={CPU O(mlog(n))}, cite={topcoder:node}] combined.log-519- -- combined.log-559- [] combined.log-560- combined.log-561-) [10] combined.log-562-\openout2 = `references.aux'. combined.log-563- combined.log-564- (./references.tex combined.log-565- combined.log:566:! LaTeX Error: \include cannot be nested. combined.log-567- combined.log-568-See the LaTeX manual or LaTeX Companion for explanation. combined.log-569-Type H <return> for immediate help. combined.log-570- ... combined.log-571- combined.log-572-l.1 \include{timeUse.tex} Bibs.bib @misc{ Gundersen, author = "G. Gundersen", title = "Data Structures in Java for Matrix Computations", year = "2002" } @book{ Lennart, author = "R. Lennart", title = "Mathematics Handbook for Science and Engineering BETA", year = "2004" }

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Jumping onto next string when the condition is met

- by user98235

This was a problem related to one of the past topcoder exam problems called HowEasy. Let's assume that we're given a sentence, for instance, "We a1re really awe~~~some" I just wanted to take get rid of every word in the sentence that doesn't contain alphabet characters, so in the above sentence, the desired output would be "We really" The below is the code I wrote (incomplete), and I don't know how to move on to the next string when the condition (the string contains a character that's not alphabet) is met. Could you suggest some revisions or methods that would allow me to do that? vect would be the vector of strings containing the desired output string param; cin>>param; stringstream ss(param); vector<string> vect; string c; while(ss >> c){ for(int i=0; i < c.length(); i++){ if(!(97<=int(c[i])&&int(c[i])<=122) && !(65<=int(c[i])&&int(c[i])<=90)){ //I want to jump onto next string once the above condition is met //and ignore string c; } vect.push_back(c); if (ss.peek() == ' '){ ss.ignore(); } } }

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being able to solve google code jam problem sets

- by JPro

This is not a homework question, but rather my intention to know if this is what it takes to learn programming. I keep loggin into TopCoder not to actually participate but to get the basic understand of how the problems are solved. But to my knowledge I don't understand what the problem is and how to translate the problem into an algorithm that can solve it. Just now I happen to look at ACM ICPC 2010 World Finals which is being held in china. The teams were given problem sets and one of them is this: Given at most 100 points on a plan with distinct x-coordinates, find the shortest cycle that passes through each point exactly once, goes from the leftmost point always to the right until it reaches the rightmost point, then goes always to the left until it gets back to the leftmost point. Additionally, two points are given such that the the path from left to right contains the first point, and the path from right to left contains the second point. This seems to be a very simple DP: after processing the last k points, and with the first path ending in point a and the second path ending in point b, what is the smallest total length to achieve that? This is O(n^2) states, transitions in O(n). We deal with the two special points by forcing the first path to contain the first one, and the second path contain the second one. Now I have no idea what I am supposed to solve after reading the problem set. and there's an other one from google code jam: Problem In a big, square room there are two point light sources: one is red and the other is green. There are also n circular pillars. Light travels in straight lines and is absorbed by walls and pillars. The pillars therefore cast shadows: they do not let light through. There are places in the room where no light reaches (black), where only one of the two light sources reaches (red or green), and places where both lights reach (yellow). Compute the total area of each of the four colors in the room. Do not include the area of the pillars. Input * One line containing the number of test cases, T. Each test case contains, in order: * One line containing the coordinates x, y of the red light source. * One line containing the coordinates x, y of the green light source. * One line containing the number of pillars n. * n lines describing the pillars. Each contains 3 numbers x, y, r. The pillar is a disk with the center (x, y) and radius r. The room is the square described by 0 = x, y = 100. Pillars, room walls and light sources are all disjoint, they do not overlap or touch. Output For each test case, output: Case #X: black area red area green area yellow area Is it required that people who program should be should be able to solve these type of problems? I would apprecite if anyone can help me interpret the google code jam problem set as I wish to participate in this years Code Jam to see if I can do anthing or not. Thanks.

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