diff --git a/leetcode/src/78.c b/leetcode/src/78.c
new file mode 100644
index 00000000..2ab7d9a5
--- /dev/null
+++ b/leetcode/src/78.c
@@ -0,0 +1,45 @@
+/**
+ * Return an array of arrays of size *returnSize.
+ * The sizes of the arrays are returned as *returnColumnSizes array.
+ * Note: Both returned array and *columnSizes array must be malloced, assume
+ * caller calls free().
+ */
+int** subsets(int* nums, int numsSize, int* returnSize, int** returnColumnSizes)
+{
+    int numSubsets = (int)pow(2, numsSize);
+
+    // Allocate memory for the result array
+    int** result = (int**)malloc(numSubsets * sizeof(int*));
+    *returnColumnSizes = (int*)malloc(numSubsets * sizeof(int));
+
+    // Initialize the sizes of individual subsets
+    for (int i = 0; i < numSubsets; i++)
+    {
+        int subsetSize = 0;
+        for (int j = 0; j < numsSize; j++)
+        {
+            if ((i >> j) & 1)
+            {
+                subsetSize++;
+            }
+        }
+        (*returnColumnSizes)[i] = subsetSize;
+    }
+
+    // Generate all subsets
+    for (int i = 0; i < numSubsets; i++)
+    {
+        result[i] = (int*)malloc((*returnColumnSizes)[i] * sizeof(int));
+        int index = 0;
+        for (int j = 0; j < numsSize; j++)
+        {
+            if ((i >> j) & 1)
+            {
+                result[i][index++] = nums[j];
+            }
+        }
+    }
+
+    *returnSize = numSubsets;
+    return result;
+}
diff --git a/leetcode/src/90.c b/leetcode/src/90.c
new file mode 100644
index 00000000..4670939e
--- /dev/null
+++ b/leetcode/src/90.c
@@ -0,0 +1,61 @@
+/**
+ * Return an array of arrays of size *returnSize.
+ * The sizes of the arrays are returned as *returnColumnSizes array.
+ * Note: Both returned array and *columnSizes array must be malloced, assume
+ * caller calls free().
+ */
+int compare(const void *a, const void *b) { return (*(int *)a - *(int *)b); }
+
+// Recursive function to generate subsets with duplicates
+void generateSubsetsWithDup(int *nums, int numsSize, int startIndex,
+                            int *currentSubset, int currentSize, int ***result,
+                            int **columnSizes, int *returnSize)
+{
+    // Add the current subset to the result
+    (*result) = (int **)realloc((*result), (*returnSize + 1) * sizeof(int *));
+    (*columnSizes) =
+        (int *)realloc((*columnSizes), (*returnSize + 1) * sizeof(int));
+
+    (*result)[*returnSize] = (int *)malloc(currentSize * sizeof(int));
+    memcpy((*result)[*returnSize], currentSubset, currentSize * sizeof(int));
+
+    (*columnSizes)[*returnSize] = currentSize;
+
+    (*returnSize)++;
+
+    // Generate subsets by including the current element
+    for (int i = startIndex; i < numsSize; i++)
+    {
+        // Skip duplicates
+        if (i > startIndex && nums[i] == nums[i - 1])
+        {
+            continue;
+        }
+
+        // Add the current element to the current subset
+        currentSubset[currentSize] = nums[i];
+        generateSubsetsWithDup(nums, numsSize, i + 1, currentSubset,
+                               currentSize + 1, result, columnSizes,
+                               returnSize);
+    }
+}
+
+int **subsetsWithDup(int *nums, int numsSize, int *returnSize,
+                     int **returnColumnSizes)
+{
+    // Sort the input array to handle duplicates
+    qsort(nums, numsSize, sizeof(int), compare);
+
+    int **result = NULL;
+    int *columnSizes = NULL;
+    int *currentSubset = (int *)malloc(numsSize * sizeof(int));
+    *returnSize = 0;
+
+    generateSubsetsWithDup(nums, numsSize, 0, currentSubset, 0, &result,
+                           &columnSizes, returnSize);
+
+    free(currentSubset);
+
+    *returnColumnSizes = columnSizes;
+    return result;
+}