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-rw-r--r--sort_matrix_by_diagonals.c93
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+// 3446. Sort Matrix by Diagonals
+#include "leetcode.h"
+
+/*
+ * you are given an 'n x n' square matrix of integers 'grid'. return the matrix
+ * such that the diagonals in the bottom left triangle including the middle are
+ * sorted in non-increasing order. the diagonals in the top-right triangle are
+ * sorted in non-decreasing order.
+ */
+
+int cmp1(const void *a, const void *b) { return (*(int *)a - *(int *)b); }
+
+int cmp2(const void *a, const void *b) { return (*(int *)b - *(int *)a); }
+
+int **sortMatrix(int **grid, int gridSize, int *gridColSize, int *returnSize,
+ int **returnColumnSizes) {
+ *returnSize = gridSize;
+ *returnColumnSizes = gridColSize;
+ int n = gridSize, m = gridColSize[0];
+ int diag_cnt = n + m - 1;
+ int *sizes = (int *)calloc(diag_cnt, sizeof(int));
+ int **diags = (int **)malloc(diag_cnt * sizeof(int *));
+ for (int i = 0; i < n; i++)
+ for (int j = 0; j < m; j++)
+ sizes[i - j + m - 1]++;
+ for (int k = 0; k < diag_cnt; k++) {
+ diags[k] = (int *)malloc(sizes[k] * sizeof(int));
+ sizes[k] = 0;
+ }
+ for (int i = 0; i < n; i++)
+ for (int j = 0; j < m; j++)
+ diags[i - j + m - 1][sizes[i - j + m - 1]++] = grid[i][j];
+ for (int k = 0; k < diag_cnt; k++) {
+ if (k < m - 1)
+ qsort(diags[k], sizes[k], sizeof(int), cmp1);
+ else
+ qsort(diags[k], sizes[k], sizeof(int), cmp2);
+ sizes[k] = 0;
+ }
+ for (int i = 0; i < n; i++)
+ for (int j = 0; j < m; j++)
+ grid[i][j] = diags[i - j + m - 1][sizes[i - j + m - 1]++];
+ for (int i = 0; i < diag_cnt; i++)
+ free(diags[i]);
+ free(diags);
+ free(sizes);
+ return grid;
+}
+
+int main() {
+ int g1i[3][3] = {{1, 7, 3}, {9, 8, 2}, {4, 5, 6}}, rs1, *rcs1;
+ int g2i[2][2] = {{0, 1}, {1, 2}}, rs2, *rcs2;
+ int g3i[1][1] = {{1}}, rs3, *rcs3;
+ struct two_d_arr *g1 =
+ two_d_arr_init(ARRAY_SIZE(g1i), ARRAY_SIZE(g1i[0]), g1i);
+ struct two_d_arr *g2 =
+ two_d_arr_init(ARRAY_SIZE(g2i), ARRAY_SIZE(g2i[0]), g2i);
+ struct two_d_arr *g3 =
+ two_d_arr_init(ARRAY_SIZE(g3i), ARRAY_SIZE(g3i[0]), g3i);
+ int **sm1 = sortMatrix(g1->arr, g1->row_size, g1->col_size, &rs1, &rcs1);
+ int **sm2 = sortMatrix(g2->arr, g2->row_size, g2->col_size, &rs2, &rcs2);
+ int **sm3 = sortMatrix(g3->arr, g3->row_size, g3->col_size, &rs3, &rcs3);
+ for (int i = 0; i < rs1; i++) {
+ for (int j = 0; j < rcs1[i]; j++)
+ printf("%d ", sm1[i][j]); // expect: [[8,2,3],[9,6,7],[4,5,1]]
+ printf("\n");
+ }
+ for (int i = 0; i < rs2; i++) {
+ for (int j = 0; j < rcs2[i]; j++)
+ printf("%d ", sm2[i][j]); // expect: [[2,1],[1,0]]
+ printf("\n");
+ }
+ for (int i = 0; i < rs3; i++) {
+ for (int j = 0; j < rcs3[i]; j++)
+ printf("%d ", sm3[i][j]); // expect: [[1]]
+ printf("\n");
+ }
+ for (int i = 0; i < rs1; i++)
+ free(sm1[i]);
+ free(sm1);
+ for (int i = 0; i < rs2; i++)
+ free(sm2[i]);
+ free(sm2);
+ for (int i = 0; i < rs3; i++)
+ free(sm3[i]);
+ free(sm3);
+ free(rcs1);
+ free(rcs2);
+ free(rcs3);
+ two_d_arr_free(g1);
+ two_d_arr_free(g2);
+ two_d_arr_free(g3);
+}