Merge K sorted lists

Signed-off-by: begeekmyfriend <[email protected]>

023_merge_k_sorted_lists/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test merge_lists.c

023_merge_k_sorted_lists/merge_lists.c

@@ -0,0 +1,91 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+
+struct ListNode {
+    int val;
+    struct ListNode *next;
+};
+
+struct ListNode* mergeKLists(struct ListNode** lists, int listsSize) {
+    if (listsSize == 0) {
+        return NULL;
+    }
+    if (listsSize == 1) {
+        return lists[0];
+    }
+
+    int i, index;
+    struct ListNode dummy, *p, *prev;
+
+    dummy.next = NULL;
+    prev = &dummy;
+    index = 0;
+    while (index != -1) {
+        int min = INT_MAX;
+        index = -1;
+        for (i = 0; i < listsSize; i++) {
+            if (lists[i] != NULL && lists[i]->val < min) {
+                min = lists[i]->val;
+                index = i;
+            }
+        }
+
+        if (index != -1) {
+            p = malloc(sizeof(*p));
+            p->val = min;
+            p->next = NULL;
+            prev->next = p;
+            prev = p;
+            lists[index] = lists[index]->next;
+        }
+    }
+
+    return dummy.next;
+}
+
+int main(void)
+{
+    int i, size;
+    struct ListNode *p, *prev, *sorted, dummy1, dummy2, **lists;
+
+    dummy1.next = NULL;
+    prev = &dummy1;
+    for (i = 0; i < 3; i++) {
+        p = malloc(sizeof(*p));
+        p->val = i * 2;
+        p->next = NULL;
+        prev->next = p;
+        prev = p;
+    }
+    for (p = dummy1.next; p != NULL; p = p->next) {
+        printf("%d ", p->val);
+    }
+    putchar('\n');
+
+    dummy2.next = NULL;
+    prev = &dummy2;
+    for (i = 0; i < 5; i++) {
+        p = malloc(sizeof(*p));
+        p->val = i * 2 + 1;
+        p->next = NULL;
+        prev->next = p;
+        prev = p;
+    }
+    for (p = dummy2.next; p != NULL; p = p->next) {
+        printf("%d ", p->val);
+    }
+    putchar('\n');
+
+    size = 2;
+    lists = malloc(size * sizeof(struct ListNode *));
+    lists[0] = NULL;//dummy1.next;
+    lists[1] = NULL;//dummy2.next;
+    sorted = mergeKLists(lists, size);
+    for (p = sorted; p != NULL; p = p->next) {
+        printf("%d ", p->val);
+    }
+    putchar('\n');
+
+    return 0;
+}