%ProjectEuler/Octave/Problem11.m %Matthew Ellison % Created: %Modified: 03-28-19 %What is the greatest product of four adjacent numbers in the same direction (up, down, left, right, or diagonally) in the 20×20 grid? %{ 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 %} %{ Copyright (C) 2019 Matthew Ellison This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see . %} %Create your variables grid = [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]; currentLocation = [1, 1]; %The location you are checking now currentProduct = [0 0 0 0]; %The product you are currently looking at greatestProduct = [0 0 0 0]; %The greatest product of values you have found finished = false; %Start the timer startTime = clock(); %Loop until you reach the last element while(~finished) left = false; right = false; down = false; %Check which directions you can go %When moving you will be moving 4 locations if((currentLocation(2) - 3) >= 1) left = true; end if((currentLocation(2) + 3) <= size(grid)(2)) right = true; end if((currentLocation(1) + 3) <= size(grid)(1)) down = true; end %Check the possible directions and check against greatest %Right if(right) currentProduct = grid(currentLocation(1), currentLocation(2):(currentLocation(2) + 3)); %If the current numbers' product is greater than the greatest product so far, replace it if(prod(currentProduct) > prod(greatestProduct)) greatestProduct = currentProduct; end end %Down if(down) currentProduct = grid(currentLocation(1):(currentLocation(1) + 3), currentLocation(2)); %If the current numbers' product is greater than the greatest product so far, replace it if(prod(currentProduct) > prod(greatestProduct)) greatestProduct = currentProduct; end end %LeftDown if(left && down) currentProduct(1) = grid(currentLocation(1), currentLocation(2)); currentProduct(2) = grid(currentLocation(1) + 1,currentLocation(2) - 1); currentProduct(3) = grid(currentLocation(1) + 2,currentLocation(2) - 2); currentProduct(4) = grid(currentLocation(1) + 3,currentLocation(2) - 3); %If the current numbers' product is greater than the greatest product so far, replace it if(prod(currentProduct) > prod(greatestProduct)) greatestProduct = currentProduct; end end %RightDown if(right && down) currentProduct(1) = grid(currentLocation(1), currentLocation(2)); currentProduct(2) = grid(currentLocation(1) + 1,currentLocation(2) + 1); currentProduct(3) = grid(currentLocation(1) + 2,currentLocation(2) + 2); currentProduct(4) = grid(currentLocation(1) + 3,currentLocation(2) + 3); %If the current numbers' product is greater than the greatest product so far, replace it if(prod(currentProduct) > prod(greatestProduct)) greatestProduct = currentProduct; end end %Move to the next column ++currentLocation(2); %If you have moved too far in the columns move back to the beginning and to the next row if(currentLocation(2) > size(grid)(2)) currentLocation(2) = 1; ++currentLocation(1); end %If the row is currently greater than what is available you have traversed the list if(currentLocation(1) > size(grid)(1)) finished = true; end end greatestProduct = reshape(greatestProduct, 1, 4); %For some reason it is coming out a 4X1 instead of 1X4 %Stop the timer endTime = clock(); %Print the result printf("The greatest product of 3 numbers in a line is %d\n", prod(greatestProduct)) printf("It took %f seconds to run this algorithm\n", etime(endTime, startTime)) %Cleanup the variables clear down; clear right; clear left; clear finished; clear startTime; clear endTime; clear grid; clear greatestProduct; clear currentLocation; clear currentProduct; clear ans; %{ Results: The greatest product of 3 numbers in a line is 70600674 It took 0.081856 seconds to run this algorithm %}