Problem:
The problem is to get the second largest array element.
Observation:
Second largest number is defined as the number that has the minimum difference when subtracted from the maximum element in the array.
Solution:
This is a two pass solution. First pass is to find the maximum number. Second pass is to find the element that has minimum difference with the maximum element as compared to other array elements. Example: In the array [2, 3, 6, 6, 5] maximum = 6 and second maximum = 5 , since it has the minimum difference to the maximum element 6 - 5 = 1 the solution for second largest = 5
function printSecondMax(myArray) {
var x, max = myArray[0];
// Find maximum element
for(x in myArray){
if(max < myArray[x]){
max = myArray[x];
}
}
var secondMax = myArray[0], diff = max - secondMax;
// Find second max, an element that has min diff with the max
for(x in myArray){
if(diff != 0 && (max - myArray[x]) != 0 && diff > (max - myArray[x])){
secondMax = myArray[x];
diff = max - secondMax;
}
}
console.log(secondMax);
}
Complexity : O(n), This is the simplest way to do this.
For finding maximum element even more efficiently one can look into max heap, a call to max-heapify will take O(log n) time to find the max and then pop-ing the top element gives maximum. To get the second maximum, max-heapify after pop-ing the top and keep pop-ing till you get a number that is less than maximum. That will be the second maximum. This solution has O(n log n) complexity.
second highestbesecond_highest? Is there a loop?