added the code for problem generate-parenthesis.c

leetcode/src/generate-parenthesis.c

@@ -0,0 +1,46 @@
+// Problem Link: https://leetcode.com/problems/generate-parentheses/ 
+// Title: 22. Generate Parentheses
+
+// This C program generates all valid combinations of n pairs of parentheses.
+// It uses a recursive approach with backtracking to explore and construct valid combinations.
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+void generateParenthesisRecursive(char **result, int *returnSize, char *current, int open, int close, int n) {
+    if (strlen(current) == 2 * n) {
+        result[(*returnSize)] = strdup(current);
+        (*returnSize)++;
+        return;
+    }
+
+    if (open < n) {
+        current[strlen(current)] = '(';
+        generateParenthesisRecursive(result, returnSize, current, open + 1, close, n);
+        current[strlen(current) - 1] = '\0';  // Backtrack
+    }
+
+    if (close < open) {
+        current[strlen(current)] = ')';
+        generateParenthesisRecursive(result, returnSize, current, open, close + 1, n);
+        current[strlen(current) - 1] = '\0';  // Backtrack
+    }
+}
+
+char **generateParenthesis(int n, int *returnSize) {
+    int maxCombinations = 10000;  // Maximum number of combinations
+    char **result = (char **)malloc(maxCombinations * sizeof(char *));
+    *returnSize = 0;
+
+    char *current = (char *)malloc(2 * n + 1); // Allocate enough memory for the parentheses and null terminator
+    memset(current, 0, 2 * n + 1);
+
+    generateParenthesisRecursive(result, returnSize, current, 0, 0, n);
+    
+    free(current);
+
+    return result;
+}
+