I][j] of size n x m where n and m are positive integers. The array A represents a grid where each element A[i][j] represents the height of the terrain at position (i, j).

To find the highest peak in this terrain, we can iterate through each element in the array and keep track of the maximum height encountered so far.

Here is a step-by-step algorithm to find the highest peak in the 2D array:

1. Initialize a variable max_height to store the maximum height encountered. Set max_height to the minimum possible value for the height (e.g., -infinity).

2. Iterate through each element in the array using two nested loops. The outer loop iterates over the rows of the array (i.e., from 0 to n-1), and the inner loop iterates over the columns of the array (i.e., from 0 to m-1).

3. For each element A[i][j], compare its height with the current maximum height. If A[i][j] is greater than max_height, update max_height to A[i][j].

4. After iterating through all elements in the array, max_height will contain the highest peak in the terrain.

5. Return max_height as the highest peak in the terrain.

Here is the pseudocode for the algorithm:

function findHighestPeak(A):
max_height = -infinity
n = length(A) // number of rows in A
m = length(A[0]) // number of columns in A
for i = 0 to n-1:
for j = 0 to m-1:
if A[i][j] > max_height:
max_height = A[i][j]
return max_height

The time complexity of this algorithm is O(n * m) since we iterate through each element in the 2D array exactly once.