702949. Value equal to index value
Value Equal to Index Value
Summary
The problem is about finding all elements in an array that are equal to their indices. This means that if the index of an element is i, then the value of the element should be i. For example, if the input array is [1, 2, 3, 4, 5, 6], the output should be [1, 4] because these are the elements that are equal to their indices.
The key concepts involved in this problem are arrays and searching.
Detailed Explanation
To solve this problem, we need to iterate through the array and check each element. If an element is equal to its index, we add it to our result set.
Here's a step-by-step breakdown of the solution:
- Initialize an empty list or array to store the elements that are equal to their indices.
- Iterate through the input array using a for loop or any other suitable method.
- For each element in the array, check if its value is equal to its index.
- If the element's value is equal to its index, add it to our result set.
- Return the result set.
Here's an example diagram of the algorithm:
Index 0: [1] -> Add to result
Index 1: [2] -> Do not add (because 2 != 1)
Index 2: [3] -> Do not add (because 3 != 2)
Index 3: [4] -> Add to result
Index 4: [5] -> Do not add (because 5 != 4)
Index 5: [6] -> Do not add (because 6 != 5)
Result: [1, 4]
The time complexity of this algorithm is O(n), where n is the size of the input array. This is because we need to iterate through each element in the array once.
The space complexity of this algorithm is O(n), where n is the number of elements that are equal to their indices. This is because we need to store these elements in our result set.
Optimized Solutions
Java
import java.util.ArrayList;
import java.util.List;
public List<Integer> valueEqualIndex(int[] arr) {
List<Integer> result = new ArrayList<>();
for (int i = 0; i < arr.length; i++) {
if (arr[i] == i) {
result.add(arr[i]);
}
}
return result;
}