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Diffstat (limited to 'transform_to_chessboard.c')
-rw-r--r-- | transform_to_chessboard.c | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/transform_to_chessboard.c b/transform_to_chessboard.c new file mode 100644 index 0000000..efe2031 --- /dev/null +++ b/transform_to_chessboard.c @@ -0,0 +1,57 @@ +// 782. Transform to Chessboard +#include "leetcode.h" + +/* + * you are given an 'n * n' binary grid 'board'. in each move, you can swap any + * two rows with each other, or any two columns with each other. return the + * minimum number of rwos to transform the board intoa chessboard board. if the + * task is impossible, return -1. a chessboard board is a board where no 0's and + * no 1's are 4-directionally adjacent + */ + +int movesToChessboard(int **board, int boardSize, int *boardColSize) { + int n = boardSize, row_sum = 0, col_sum = 0, row_swap = 0, col_swap = 0; + for (int i = 0; i < n; ++i) + for (int j = 0; j < n; ++j) + if (board[0][0] ^ board[i][0] ^ board[0][j] ^ board[i][j]) + return -1; + for (int i = 0; i < n; ++i) { + row_sum += board[0][i]; + col_sum += board[i][0]; + row_swap += board[i][0] == i % 2; + col_swap += board[0][i] == i % 2; + } + if (row_sum != n / 2 && row_sum != (n + 1) / 2) + return -1; + if (col_sum != n / 2 && col_sum != (n + 1) / 2) + return -1; + if (n % 2) { + if (col_swap % 2) + col_swap = n - col_swap; + if (row_swap % 2) + row_swap = n - row_swap; + } else { + col_swap = fmin(n - col_swap, col_swap); + row_swap = fmin(n - row_swap, row_swap); + } + return (col_swap + row_swap) / 2; +} + +int main() { + int b1i[4][4] = {{0, 1, 1, 0}, {0, 1, 1, 0}, {1, 0, 0, 1}, {1, 0, 0, 1}}; + int b2i[2][2] = {{0, 1}, {1, 0}}; + int b3i[2][2] = {{1, 0}, {1, 0}}; + struct two_d_arr b1, b2, b3; + two_d_arr_init(&b1, 4, 4, b1i); + two_d_arr_init(&b2, 2, 2, b2i); + two_d_arr_init(&b3, 2, 2, b3i); + printf("%d\n", + movesToChessboard(b1.arr, b2.row_size, b3.col_size)); // expect: 2 + printf("%d\n", + movesToChessboard(b2.arr, b2.row_size, b2.col_size)); // expect: 0 + printf("%d\n", + movesToChessboard(b3.arr, b3.row_size, b3.col_size)); // expect: -1 + two_d_arr_free(&b1); + two_d_arr_free(&b2); + two_d_arr_free(&b3); +} |