// In the 2020 grid below, four numbers along a diagonal line have been marked in red.
//
// 08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
// 49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
// 81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
// 52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
// 22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
// 24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
// 32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
// 67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
// 24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
// 21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
// 78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
// 16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
// 86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
// 19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
// 04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
// 88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
// 04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
// 20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
// 20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
// 01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48
// The product of these numbers is 26 63 78 14 = 1788696.
//
// What is the greatest product of four adjacent numbers in any direction (up, down, left, right, or diagonally) in the 2020 grid?
using System;
using System.Collections.Generic;
using System.Text;
namespace projecteuler011
{
class Program
{
static void Main(string[] args)
{
F1();
}
private static void F1()
{
Console.WriteLine(new System.Diagnostics.StackTrace().GetFrame(0).GetMethod());
DateTime timeStart = DateTime.Now;
int[][] data = new int[][]{
new int[]{08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08},
new int[]{49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62,00},
new int[]{81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65},
new int[]{52,70,95,23,04,60,11,42,69,24,68,56,01,32,56,71,37,02,36,91},
new int[]{22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80},
new int[]{24,47,32,60,99,03,45,02,44,75,33,53,78,36,84,20,35,17,12,50},
new int[]{32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70},
new int[]{67,26,20,68,02,62,12,20,95,63,94,39,63,08,40,91,66,49,94,21},
new int[]{24,55,58,05,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72},
new int[]{21,36,23,09,75,00,76,44,20,45,35,14,00,61,33,97,34,31,33,95},
new int[]{78,17,53,28,22,75,31,67,15,94,03,80,04,62,16,14,09,53,56,92},
new int[]{16,39,05,42,96,35,31,47,55,58,88,24,00,17,54,24,36,29,85,57},
new int[]{86,56,00,48,35,71,89,07,05,44,44,37,44,60,21,58,51,54,17,58},
new int[]{19,80,81,68,05,94,47,69,28,73,92,13,86,52,17,77,04,89,55,40},
new int[]{04,52,08,83,97,35,99,16,07,97,57,32,16,26,26,79,33,27,98,66},
new int[]{88,36,68,87,57,62,20,72,03,46,33,67,46,55,12,32,63,93,53,69},
new int[]{04,42,16,73,38,25,39,11,24,94,72,18,08,46,29,32,40,62,76,36},
new int[]{20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74,04,36,16},
new int[]{20,73,35,29,78,31,90,01,74,31,49,71,48,86,81,16,23,57,05,54},
new int[]{01,70,54,71,83,51,54,69,16,92,33,48,61,43,52,01,89,19,67,48}};
int maxProduct = int.MinValue;
//1.找出横着方向的最大值
for (int i = 0; i < 20; i++)
{
maxProduct = Math.Max(maxProduct, FindMaxProduct(data[i], 4));
}
//2.找出竖着方向的最大值
for (int i = 0; i < 20; i++)
{
maxProduct = Math.Max(maxProduct, FindMaxProduct(getVerticalArray(data, i), 4));
}
//3.找出右斜方向的最大值
for (int i = -16; i <= 16; i++)
{
maxProduct = Math.Max(maxProduct, FindMaxProduct(getRightDiagonalArray(data, i), 4));
}
//4.找出左斜方向的最大值
for (int i = 3; i <= 35; i++)
{
maxProduct = Math.Max(maxProduct, FindMaxProduct(getLeftDiagonalArray(data, i), 4));
}
Console.WriteLine(maxProduct);
Console.WriteLine("Total Milliseconds is " + DateTime.Now.Subtract(timeStart).TotalMilliseconds + "\n\n");
}
/// <summary>
/// 找出一段中连续n个数相乘的最大值
/// </summary>
/// <param name="data"></param>
/// <param name="n"></param>
private static int FindMaxProduct(int[] data, int n)
{
int maxProduct = int.MinValue;
int currentProduct = 1;
int currentDig = 0;
int length = data.Length;
for (int i = 0; i < length; i++)
{
if (data[i] == 0)
{
currentDig = 0;
continue;
}
if (currentDig == 0)
{
currentProduct = data[i];
currentDig = 1;
continue;
}
if (currentDig < n)
{
currentProduct *= data[i];
currentDig++;
}
else if (i > n - 1)
{
currentProduct /= data[i - n];
currentProduct *= data[i];
if (currentProduct > maxProduct)
{
maxProduct = currentProduct;
}
}
}
return maxProduct;
}
/// <summary>
/// 找出第n列的数组
/// </summary>
/// <param name="data"></param>
/// <param name="n"></param>
/// <returns></returns>
private static int[] getVerticalArray(int[][] data, int n)
{
int length = data.Length;
int[] result = new int[length];
for (int i = 0; i < length; i++)
{
result[i] = data[i][n];
}
return result;
}
/// <summary>
/// 找出右斜的数组，范围-16~16
/// </summary>
/// <param name="data"></param>
/// <param name="n"></param>
/// <returns></returns>
private static int[] getRightDiagonalArray(int[][] data, int n)
{
int[] result;
int length; //数组长度
if (n >= 0) //右上部分
{
length = 20 - n;
result = new int[length];
for (int i = 0; i < length; i++)
{
result[i] = data[i][i + n];
}
}
else //左下部分
{
length = 20 + n;
result = new int[length];
for (int i = 0; i < length; i++)
{
result[i] = data[i - n][i];
}
}
return result;
}
/// <summary>
/// 找出左斜的数组，范围3~35
/// </summary>
/// <param name="data"></param>
/// <param name="n"></param>
/// <returns></returns>
private static int[] getLeftDiagonalArray(int[][] data, int n)
{
int[] result;
int length; //数组长度
if (n <= 19) //左上部分
{
length = n + 1;
result = new int[length];
for (int i = 0; i < length; i++)
{
result[i] = data[n - i][i];//3 0 2 1 1 2 0 3 n=3
}
}
else //右下部分
{
length = 39 - n;
result = new int[length];
for (int i = 0; i < length; i++)
{
result[i] = data[19 - i][n + i - 19];//19 1 18 2 17 3 16 4 n=20
//19 2 18 3 17 4 16 5 n=21
}
}
return result;
}
}
}
/*
Void F1()
70600674
Total Milliseconds is 10.5014
By GodMoon
*/
