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Find Second Largest in Array - Optimal Approach

Find Second Largest in Array - Optimal Approach

Visualization

Algorithm Steps

  1. Given an array of numbers arr.
  2. Initialize max_val and second_max to -Infinity.
  3. Iterate through each element in the array.
  4. If the current element is greater than max_val, update second_max to max_val, and then update max_val.
  5. Else if the current element is greater than second_max and not equal to max_val, update second_max.
  6. After the loop, return second_max.

Find Second Largest using Loop - Optimal Approach Code

Python
JavaScript
Java
C++
C
def find_second_largest(arr):
    max_val = float('-inf')
    second_max = float('-inf')
    for num in arr:
        if num > max_val:
            second_max = max_val
            max_val = num
        elif num > second_max and num != max_val:
            second_max = num
    return second_max

# Sample Input
arr = [30, 20, 10, 50, 60, 40]
print("Second Largest:", find_second_largest(arr))

Detailed Step by Step Example

Let's find the second largest number in the array using a loop.

{ "array": [30,20,10,50,60,40], "showIndices": true }

Initialize max = -Infinity and secondMax = -Infinity.

Check index 0

Current element is 30. Compare with max = -Infinity and secondMax = -Infinity.

30 is greater than current max. Update: secondMax = -Infinity, max = 30.

{ "array": [30,20,10,50,60,40], "showIndices": true, "highlightIndices": [0], "labels": {"0":"i"} }
{ "array": [0,30,null], "showIndices": false, "emptyIndices": [1, 2], "emptyCompIndices": [0], "labels": { "1": "max", "2": "secondMax" } }

Check index 1

Current element is 20. Compare with max = 30 and secondMax = -Infinity.

20 is greater than current secondMax and not equal to max. Update: secondMax = 20.

{ "array": [30,20,10,50,60,40], "showIndices": true, "highlightIndices": [1], "labels": {"1":"i"} }
{ "array": [0,30,20], "showIndices": false, "emptyIndices": [1, 2], "emptyCompIndices": [0], "labels": { "1": "max", "2": "secondMax" } }

Check index 2

Current element is 10. Compare with max = 30 and secondMax = 20.

No update required.

{ "array": [30,20,10,50,60,40], "showIndices": true, "highlightIndices": [2], "labels": {"2":"i"} }
{ "array": [0,30,20], "showIndices": false, "emptyIndices": [1, 2], "emptyCompIndices": [0], "labels": { "1": "max", "2": "secondMax" } }

Check index 3

Current element is 50. Compare with max = 30 and secondMax = 20.

50 is greater than current max. Update: secondMax = 30, max = 50.

{ "array": [30,20,10,50,60,40], "showIndices": true, "highlightIndices": [3], "labels": {"3":"i"} }
{ "array": [0,50,30], "showIndices": false, "emptyIndices": [1, 2], "emptyCompIndices": [0], "labels": { "1": "max", "2": "secondMax" } }

Check index 4

Current element is 60. Compare with max = 50 and secondMax = 30.

60 is greater than current max. Update: secondMax = 50, max = 60.

{ "array": [30,20,10,50,60,40], "showIndices": true, "highlightIndices": [4], "labels": {"4":"i"} }
{ "array": [0,60,50], "showIndices": false, "emptyIndices": [1, 2], "emptyCompIndices": [0], "labels": { "1": "max", "2": "secondMax" } }

Check index 5

Current element is 40. Compare with max = 60 and secondMax = 50.

No update required.

{ "array": [30,20,10,50,60,40], "showIndices": true, "highlightIndices": [5], "labels": {"5":"i"} }
{ "array": [0,60,50], "showIndices": false, "emptyIndices": [1, 2], "emptyCompIndices": [0], "labels": { "1": "max", "2": "secondMax" } }

Final Result:

Second Largest Element = 50

{ "array": [30,20,10,50,60,40], "showIndices": true, "labels": { "4": "max", "3": "secondMax" } }
{ "array": [0,60,50], "showIndices": false, "emptyIndices": [1, 2], "emptyCompIndices": [0], "labels": { "1": "max", "2": "secondMax" } }