using System;
public class MaxProductOfSubarray_CSharp
{
public static int getMaxProductOfSubarray(int[] arr) {
int len = arr.Length;
if (len == 0) {
return 0;
}
int max_current_index = arr[0], min_current_index = arr[0], max_product = arr[0];
Console.Write("arr[i] = {0:D} max_current_index = {1:D} min_current_index = {2:D} max_product = {3:D}\n", arr[0], max_current_index, min_current_index, max_product);
for (int i = 1; i < len; i++) {
int temp = max_current_index;
max_current_index = Math.Max(arr[i], Math.Max(arr[i] * max_current_index, arr[i] * min_current_index));
min_current_index = Math.Min(arr[i], Math.Min(arr[i] * temp, arr[i] * min_current_index));
Console.Write("arr[i] = {0:D} max_current_index = {1:D} min_current_index = {2:D}\n", arr[i], max_current_index, min_current_index);
max_product = Math.Max(max_product, max_current_index);
Console.Write("max_product = {0:D}\n", max_product);
}
return max_product;
}
public static void Main(string[] args)
{
int[] arr = new int[] {-4, 8, 2, 5, 90, 7, 0, -3, 6}; // 8 * 2 * 5 * 90 * 7 = 50400
Console.Write("maximum product = " + getMaxProductOfSubarray(arr));
}
}
/*
run:
arr[i] = -4 max_current_index = -4 min_current_index = -4 max_product = -4
arr[i] = 8 max_current_index = 8 min_current_index = -32
max_product = 8
arr[i] = 2 max_current_index = 16 min_current_index = -64
max_product = 16
arr[i] = 5 max_current_index = 80 min_current_index = -320
max_product = 80
arr[i] = 90 max_current_index = 7200 min_current_index = -28800
max_product = 7200
arr[i] = 7 max_current_index = 50400 min_current_index = -201600
max_product = 50400
arr[i] = 0 max_current_index = 0 min_current_index = 0
max_product = 50400
arr[i] = -3 max_current_index = 0 min_current_index = -3
max_product = 50400
arr[i] = 6 max_current_index = 6 min_current_index = -18
max_product = 50400
maximum product = 50400
*/
