Find a pass of sequential values in an int array
Let's say I have this integer array of single integer elements:
111100010011010
I would like to know if this array exists 0000
, which obviously does not, but 000
does. The same applies to other lengths of successive runs.
I know it's easy to do this with strings, there are built-in functions for that, but is there something built in that does what I want to do?
Or is there another simple method that I forgot? All I can think of is complex inefficient algorithms going through an array and storing the values in a temporary other array.
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You don't need to store the values in a temporary array.
All you have to do is keep track of the largest length found (initially zero) and the location of its first element (initially NULL if you specified a pointer).
Then walk through the array until you find the value of interest. Count the number of consecutive events. If this number is greater than the maximum length found, set a location to indicate the first found.
Repeat until you reach the end of the array.
Done. If the found longest length is zero, it means that there were no values for the desired value.
No, I will not write the code for the above. The description of the approach is sufficient.
There are also many alternatives using standard algorithms.
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For writing only, another way is to use std :: search .
#include <algorithm>
using namespace std;
const int elements[] = { 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0 };
const int test1[] = { 0, 0, 0, 0 };
const int test2[] = { 0, 0, 0 };
auto it1 = std::search(begin(elements), end(elements), begin(test1), end(test1));
auto it2 = std::search(begin(elements), end(elements), begin(test2), end(test2));
std::cout << "Test 0000: " << (it1 == end(elements) ? "no" : "yes") << "\n";
std::cout << "Test 000: " << (it2 == end(elements) ? "no" : "yes") << "\n";
Prints out:
Test 0000: no
Test 000: yes
It's even easier if your array is a standard container like std :: array or vector.
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