#include #include #include /** * Project: Knight Moves Calculator * Goal: The knight moves in a unique pattern in chess. Specifically, an L shape. Thus it can be a bit tedious reaching neighboring squares. Assuming a start point of (0,0), determine the number of squares the knight will touch to reach a final destination, D(x,y). * Creator: Ace * Bugs: None known * Notes: 3 versions of this exist. One version is optimized for C-users, another for C++ users, and yet another for Sololearn use. If interested in other versions message me via Discord or leave a comment. * This code uses some linear algebra. If there are concepts foreign to you, ask away! Linear algebra allows this to be solved in O(1) time. * Basically what I did was build a giant matrix and found a pattern I could use. *Version control: *0.0.0.0 - Used Linear Algebra and pattern regconition to figure out cases for calculation. *0.0.0.1 - Separated calculation into separate function *0.0.0.2 - Code improvements, optimizations, added exception handler *0.0.0.3c - Sololearn version complete. Released */ int knightDeterminant(int, int); int main(void) { int x, y; try { puts("Enter coordinates: "); std::cin>>x>>y; if(std::cin.bad()) throw 'b'; if(std::cin.fail()) throw 'f'; if(x==0&&y==0) throw 's'; printf("%d moves\n", knightDeterminant(x, y)); }catch(char EX) { switch(EX) { case 'f': puts("Unrecoverable fail state! Probable cause is failure to input a value. Usage of this application: representing a coordinate pair on an NxN chess board."); break; case 'b': puts("Unrecoverable IO error! Probable cause is bad input. Usage of this application: representing a coordinate pair on an NxN chess board."); break; case 's': puts("0 moves."); break; } } return EXIT_SUCCESS; } int knightDeterminant(int x, int y) { int delta, xbase; /* Normalize coordinates to have 0 <= y <= x */ if (x < 0) x = -x; if (y < 0) y = -y; if (x < y) (x ^= y), (y ^= x), (x ^= y); /* Compute distance based on coordinates */ delta = x-y; if (delta < y) { /* y > 0 and x/y < 2 */ if (x == 2 && y == 2) return 4; /* Exception */ return delta+((y-delta+2)/3)*2; } else { /* y = 0 or x/y >= 2 */ if (x == 1 && y == 0) { return 3; /* Exception */ } xbase = x-(y%2)*2; return (xbase/4)*2+xbase%4+y%2; } }

KnightMoveCalculator