commit e1f151615a4f7a29be2ab4fc6210f8c803b0e343
parent c7d3cce24ad8f1e0a7164a6ce27cb9fa83bae856
Author: Jack Sangdahl <jack@pngu.org>
Date: Sat, 21 Mar 2026 20:04:42 -0600
3643. flip square submatrix vertically
Diffstat:
2 files changed, 109 insertions(+), 0 deletions(-)
diff --git a/flip_square_submat_vertically.c b/flip_square_submat_vertically.c
@@ -0,0 +1,75 @@
+// 3643. Flip Square Submatrix Vertically
+#include "leetcode.h"
+
+/*
+ * you are given an 'm x n' integer matrix 'grid', and three integers 'x', 'y',
+ * and 'k'. the integers 'x' and 'y' represent the row and column indices of the
+ * top elft corner of a square submatrix and the integer 'k' represents the size
+ * (side length) of the square submatrix. your task is to flip the submatrix by
+ * reversing the order of its rows vertically. return the updated matrix.
+ */
+
+int **reverseSubmatrix(int **grid, int gridSize, int *gridColSize, int x, int y,
+ int k, int *returnSize, int **returnColumnSizes) {
+ int m = gridSize, n = gridColSize[0];
+ *returnSize = m;
+ *returnColumnSizes = (int *)malloc(m * sizeof(int));
+ int **ans = (int **)malloc(m * sizeof(int *));
+ for (int i = 0; i < m; i++) {
+ (*returnColumnSizes)[i] = n;
+ ans[i] = (int *)malloc(n * sizeof(int));
+ for (int j = 0; j < n; j++)
+ ans[i][j] = grid[i][j];
+ }
+ for (int i = 0; i < k / 2; i++)
+ for (int j = 0; j < k; j++) {
+ int tmp = ans[x + i][y + j];
+ ans[x + i][y + j] = ans[x + k - 1 - i][y + j];
+ ans[x + k - 1 - i][y + j] = tmp;
+ }
+ return ans;
+}
+
+int main() {
+ int g1i[4][4] = {
+ {1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}};
+ int g2i[2][4] = {{3, 4, 2, 3}, {2, 3, 4, 2}};
+ 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);
+ int r1[4][4] = {
+ {1, 2, 3, 4}, {13, 14, 15, 8}, {9, 10, 11, 12}, {5, 6, 7, 16}};
+ int r2[2][4] = {{3, 4, 4, 2}, {2, 3, 2, 3}};
+ int rs1, *rcs1, rs2, *rcs2;
+ int **rvsm1 = reverseSubmatrix(g1->arr, g1->row_size, g1->col_size, 1, 0, 3,
+ &rs1, &rcs1);
+ int **rvsm2 = reverseSubmatrix(g2->arr, g2->row_size, g2->col_size, 0, 2, 2,
+ &rs2, &rcs2);
+ for (int i = 0; i < rs1; i++) {
+ for (int j = 0; j < rcs1[i]; j++) {
+ printf("%d ", rvsm1[i][j]);
+ assert(rvsm1[i][j] == r1[i][j]);
+ }
+ printf("\n");
+ }
+ printf("\n");
+ for (int i = 0; i < rs2; i++) {
+ for (int j = 0; j < rcs2[i]; j++) {
+ printf("%d ", rvsm2[i][j]);
+ assert(rvsm2[i][j] == r2[i][j]);
+ }
+ printf("\n");
+ }
+ printf("\n");
+ for (int i = 0; i < rs1; i++)
+ free(rvsm1[i]);
+ free(rvsm1);
+ free(rcs1);
+ for (int i = 0; i < rs2; i++)
+ free(rvsm2[i]);
+ free(rvsm2);
+ free(rcs2);
+ two_d_arr_free(g1);
+ two_d_arr_free(g2);
+}
diff --git a/flip_square_submat_vertically.py b/flip_square_submat_vertically.py
@@ -0,0 +1,34 @@
+# 3643. Flip Square Submatrix Vertically
+from typing import List
+
+"""
+you are given an 'm x n' integer matrix 'grid', and three integers 'x', 'y',
+and 'k'. the integers 'x' and 'y' represent the row and column indices of the
+top elft corner of a square submatrix and the integer 'k' represents the size
+(side length) of the square submatrix. your task is to flip the submatrix by
+reversing the order of its rows vertically. return the updated matrix.
+"""
+
+
+class Solution:
+ def reverseSubmatrix(
+ self, grid: List[List[int]], x: int, y: int, k: int
+ ) -> List[List[int]]:
+ for i in range(k >> 1):
+ r1, r2 = grid[x + i], grid[x + k - 1 - i]
+ for j in range(k):
+ r1[y + j], r2[y + j] = r2[y + j], r1[y + j]
+ return grid
+
+
+if __name__ == "__main__":
+ obj = Solution()
+ print(
+ obj.reverseSubmatrix(
+ grid=[[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]],
+ x=1,
+ y=0,
+ k=3,
+ )
+ )
+ print(obj.reverseSubmatrix(grid=[[3, 4, 2, 3], [2, 3, 4, 2]], x=0, y=2, k=2))
