Simple solution Java/Kotlin with O(n) Time complexity...
IntuitionApproachComplexity

Time complexity:
O(n)


Space complexity:

CodeCode
# Intuition
<!-- Describe your first thoughts on how to solve this problem. -->

# Approach
<!-- Describe your approach to solving the problem. -->

# Complexity
- Time complexity:
O(n)

- Space complexity:
<!-- Add your space complexity here, e.g. $$O(n)$$ -->

# Code
```java []
class Solution {
    public int areaOfMaxDiagonal(int[][] dimensions) {
        double diagonal = 0;
        int area = 0;
        for(int i =0; i<dimensions.length; i++){
            double d = Math.sqrt(dimensions[i][0]*dimensions[i][0] + dimensions[i][1] * dimensions[i][1]);
            if(diagonal < d){
                diagonal = d;
                area = dimensions[i][0]*dimensions[i][1];
            }else if(diagonal == d){
                if(area < dimensions[i][0]*dimensions[i][1]){
                    area = dimensions[i][0]*dimensions[i][1];
                }
            }
        
        }
        return area;
    }
}
```
# Code
```kotlin []
class Solution {
    fun areaOfMaxDiagonal(dimensions: Array<IntArray>): Int {

        var diagonal: Double = 0.0;
        var area:Int = 0;
        for(i in 0 until dimensions.size){
            val d: Double  = sqrt((dimensions[i][0]*dimensions[i][0] + dimensions[i][1] * dimensions[i][1]).toDouble());
            if(diagonal < d){
                diagonal = d;
                area = dimensions[i][0]*dimensions[i][1];
            }else if(diagonal == d){
                if(area < dimensions[i][0]*dimensions[i][1]){
                    area = dimensions[i][0]*dimensions[i][1];
                }
            }
        }

        return area;
    }
}
```
['Java', 'Kotlin']