Question

How to find the starting and ending position of a given value in a sorted integer array in C++

Answer 1

#include <vector>
#include <iostream>

std::vector<int> findStartingEndingPosition(std::vector<int> &arr, int value) {
	std::vector<int> result(2);

	result[0] = -1;
	result[1] = -1;

	int i = 0;

	for (; i < arr.size() - 1; i++) {
		if (arr[i] == value) {
			result[0] = i;
			result[1] = i;
			break;
		}
	}

	for (int j = i; j < arr.size() - 1; j++) {
		if (arr[j] == arr[j + 1]) {
			result[1] = j + 1;
		}
		else {
			break;
		}
	}

	return result;
}

int main()
{
	std::vector<int> arr = {1, 3, 4, 7, 7, 8, 8, 10, 11};
	int value = 8;

	std::vector<int> result = findStartingEndingPosition(arr, value);

	std::cout << "start: " << result[0] << std::endl;
	std::cout << "end: " << result[1] << std::endl;
}



/*
run:

start: 5
end: 6

*/

 

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