c - How to generate without repeat value in using two random () -
i generating random nos store matrix index row , column . different row , column index nos every time not repeat. time same value generating.how rectify problem.
this written .. example
4 * 4 matrix. running loop , storing date
int i; (i=0;i<6;i++) { row = arc4random() % 4 ; column = arc4random() % 4; cgfloat xoffset1 = (block.contentsize.width+350)+((block.contentsize.height-15)*column); fireblock.position = ccp(xoffset1,row*15); statement 1--- store column; statement 2--- store row; }
with 16 different combinations, i'd write of them in array, shuffle array, select array.
struct row_col_index { int row; int column; }; /* ... */ struct row_col_index all_combinations[4*4] = { {0, 0}, {0, 1}, {0, 2}, {0, 3}, {1, 0}, {1, 1}, {1, 2}, {1, 3}, {2, 0}, {2, 1}, {2, 2}, {2, 3}, {3, 0}, {3, 1}, {3, 2}, {3, 3}, }; shuffle(all_combinations); (int = 0; < 6; i++) { row = all_combinations[i].row; column = all_combinations[i].column; /* ... */ } /* ... */
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