From 522deb6f82e68596b8b4ea39153db840132a22e0 Mon Sep 17 00:00:00 2001
From: Samuel Ortion <samuel@ortion.fr>
Date: Sat, 1 Mar 2025 09:43:02 +0100
Subject: [PATCH] Solve 23: Merge K sorted lists

---
 src/23.merge-k-sorted-lists.c | 100 ++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 src/23.merge-k-sorted-lists.c

diff --git a/src/23.merge-k-sorted-lists.c b/src/23.merge-k-sorted-lists.c
new file mode 100644
index 0000000..23ff4c2
--- /dev/null
+++ b/src/23.merge-k-sorted-lists.c
@@ -0,0 +1,100 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "../includes/list.h"
+
+struct ListNode *minimumList(struct ListNode **lists, int listSize, int *minimumListIndex);
+
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     struct ListNode *next;
+ * };
+ */
+struct ListNode* mergeKLists(struct ListNode** lists, int listsSize) {
+    int minimumListIndex = 0;
+    struct ListNode* first_node = minimumList(lists, listsSize, &minimumListIndex);
+    if (first_node == NULL) {
+        return NULL;
+    } else {
+        lists[minimumListIndex] = first_node->next;
+        struct ListNode *next_node = mergeKLists(lists, listsSize);
+        first_node->next = next_node;
+    }
+    return first_node;
+}
+
+/** Find the list node with minimal value.
+ */
+struct ListNode *minimumList(struct ListNode** lists, int listsSize, int* minimumListIndex) {
+    if (listsSize < 1) {
+        return NULL;
+    } else {
+        struct ListNode *minimumNode = NULL;
+        int i=0;
+        do {
+            minimumNode = lists[i];
+            *minimumListIndex = i;
+            i++;
+        } while (i < listsSize && minimumNode == NULL);
+        while (i < listsSize) {
+            struct ListNode *node = lists[i];
+            if (node != NULL && node->val < minimumNode->val) {
+                minimumNode = node;
+                *minimumListIndex = i;
+            }
+            i++;
+        }
+        return minimumNode;
+    }
+}
+
+void test_1() {
+    int listsSize = 3;
+    struct ListNode *l1 = NULL;
+    l1 = list_insert(l1, 1);
+    l1 = list_insert(l1, 4);
+    l1 = list_insert(l1, 5);
+    struct ListNode *l2 = NULL;
+    l2 = list_insert(l2, 1);
+    l2 = list_insert(l2, 3);
+    l2 = list_insert(l2, 4);
+    struct ListNode *l3 = NULL;
+    l3 = list_insert(l3, 2);
+    l3 = list_insert(l3, 6);
+    struct ListNode **lists = malloc(3 * sizeof(struct ListNode *));
+    lists[0] = l1;
+    lists[1] = l2;
+    lists[2] = l3;
+    struct ListNode *result_list = mergeKLists(lists, listsSize);
+    if (result_list == NULL) {
+        printf("aie\n");
+    }
+    list_print(result_list);
+    list_clear(l1);
+    list_clear(l2);
+    list_clear(l3);
+}
+
+void test_2() {
+    struct ListNode **lists = NULL;
+    struct ListNode *result_list = mergeKLists(lists, 0);
+    list_print(result_list);
+    list_clear(result_list);
+}
+
+void test_3() {
+    struct ListNode *empty_list = NULL;
+    struct ListNode **lists = malloc(sizeof(struct ListNode *));
+    lists[0] = empty_list;
+    struct ListNode *result_list = mergeKLists(lists, 1);
+    list_print(result_list);
+    list_clear(result_list);
+}
+
+int main() {
+    test_1();
+    test_2();
+    test_3();
+}