// 498. Diagonal Traverse #include "leetcode.h" /* * given an 'm x n' matrix 'mat', return an array of all the elements of the * array in a diagonal order. */ int *findDiagonalOrder(int **mat, int matSize, int *matColSize, int *returnSize) { int n = matSize * matColSize[0], row = 0, col = 0; int *ans = (int *)malloc(n * sizeof(int)); *returnSize = n; for (int i = 0; i < n; i++) { ans[i] = mat[row][col]; if (!((row + col) % 2)) { if (col == matSize - 1) row++; else if (!row) col++; else { row--; col++; } } else { if (row == matColSize[0] - 1) col++; else if (!col) row++; else { row++; col--; } } } return ans; } int main() { int m1i[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}, m2i[2][2] = {{1, 2}, {3, 4}}; struct two_d_arr *m1 = two_d_arr_init(ARRAY_SIZE(m1i), ARRAY_SIZE(m1i[0]), m1i); struct two_d_arr *m2 = two_d_arr_init(ARRAY_SIZE(m2i), ARRAY_SIZE(m2i[0]), m2i); int rs1, *fdo1 = findDiagonalOrder(m1->arr, m1->row_size, m1->col_size, &rs1); int rs2, *fdo2 = findDiagonalOrder(m2->arr, m2->row_size, m2->col_size, &rs2); for (int i = 0; i < rs1; i++) printf("%d ", fdo1[i]); // expect: 1 2 4 7 5 3 6 8 9 printf("\n"); for (int i = 0; i < rs2; i++) printf("%d ", fdo2[i]); // expect: 1 2 3 4 printf("\n"); free(fdo1); free(fdo2); two_d_arr_free(m1); two_d_arr_free(m2); }