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Implementation of closest point calculation

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— Leave a comment October 4

2010 This program demonstrates the use of an array and is representative of the usual situation in which we store data in one array to process them later.
It counts the number of pairs of N randomly generated points of the unit square, which can be connected to a line segment of length less than ‘d’, using the point data type.
Because the execution time of this program is O(n2), it can’t be used for large N.
You should know that the implementation of the algorithm does not take into account issues of data input validation or proper management of dynamic memory (e.g.
avoiding memory leaks) because it is only necessary to highlight the logic of the algorithm.
Interface (point.h) of the data structure ‘point’.
#ifndef _POINT_H #define _POINT_H struct point { float x, y; }; float dist (point, .

Point); #endif // _POINT_H Implementation (point.cpp) of the data structure ‘point’

#include #include “point.h” float dist (point a, point b) { float dx = a.x – b.x; float dy = a.y – b.y; return sqrt (dx * dx + dy * dy); } Driver (main.cpp) – use of the data structure .
#include #include #include “point.h” using namespace std; float randFloat () { return 1.0 * rand () / RAND_MAX; } int main (int argc, char *argv[]) { float d; int N, i, cnt = 0; if (!argv[1] || !argv[2]) return EXIT_FAILURE; d = atof (argv[2]); N = atoi (argv[1]); srand (time (NULL)); point *a = new point[N]; for (i = 0; i < N; i++) { a[i].x = randFloat (); a[i].y = randFloat (); } for (i = 0; i < N; i++) for (int j = i + 1; j < N; j++) if (dist (a[i], a[j]) < d) cnt++; cout << cnt << " pairs within " << d << endl; return EXIT_SUCCESS; } Rate this:. Share this:. Click to share on Facebook (Opens in new window).

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« Implement simple reverse list iteratively

Implementation of insertion sort algorithm for single linked lists

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Implementation of algorithm for the calculating of prefix expressions.
Filed under: , — 4 Comments March 31, 2011 To calculate a prefix expression, we either convert a number from ASCII to decimal (in the loop ‘while’ at the end of the program) or implement the operation indicated by the first character of the expressions to the two terms, with a recursive calculation .
This function is recursive, but it uses a global array containing the expression and an index number for the current character of the expression.
The index number goes beyond each sub-expression calculated.
You should know that the implementation of the algorithm does not take into account issues of data input validation or proper management of dynamic memory (e.g.
avoiding memory leaks) because it is only necessary to highlight the logic of the algorithm.
char *expression = “+ * 4 5 6”; int i = 0; int eval () { int x = 0; while (expression[i] == ‘ ‘) i++; if (expression[i] == ‘+’) { i++; return eval () + eval (); } if (expression[i] == ‘*’) { i++; return eval () * eval (); } while ((expression[i] >= ‘0’) && (expression[i] <= '9')) x = 10 * x + (expression[i++] - '0'); return x; } Rate this:. Share this:. Click to share on Facebook (Opens in new window).

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Comments RSS feed 4 Comments:

E.
Chatzikyriakidis April 2, 2011 at 13:55 All is well.
????.

Pantelis Koukousoulas April 2

2011 at 11:50 My mistake.

I guess I read the wrong code about the wrong article ???? Sorry for the noise ????

E.
Chatzikyriakidis April 2, 2011 at 00:54 Before reaching any conclusions about whether I understand the recursion or not, you’d better study the article better.

Try the code in a C++ program to determine whether it is right or not

The program works exactly as it should and it does what it is meant to.
It is quite simple and only supports two binary operators (addition, multiplication).
If you care about something more complete, you can see a complete calculator that I have developed in the following address: https://efxa.org/arduino_infix_calculator/.
Also, if you are interested in something more sophisticated, you can study the interpreter that I have developed for the programming language YAFL: https://efxa.org/yafl-project/.
But thank you for your interest ????.

Pantelis Koukousoulas April 1

2011 at 17:57 Sorry, but this code is wrong.
Please do not use it in a real program ???? I do not think you understand how recursion works….
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« Collection of useful recursive functions

Implementation of algorithms (without recursion) for preorder & level-order traversal of binary trees.
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