add problem 23 and test function

Author: supercoderhawk

C/1-50/23-Merge-k-Sorted-Lists.c

@@ -0,0 +1,117 @@
+/*
+ * Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.
+ * Created by supercoderx on 2017/8/11.
+ */
+
+#include "../main.h"
+#include 
+#include 
+
+struct ListNode *mergeKLists(struct ListNode **lists, int listsSize) {
+    if (listsSize <= 0) {
+        return NULL;
+    }
+    if (listsSize == 1) {
+        return lists[0];
+    }
+
+    struct ListNode *header = lists[0], *p, *p1, *p2, *node, *prev;
+    int count = 0, start = 0;
+
+    for (int i = 1; i < listsSize; i++) {
+        p1 = header;
+        p2 = lists[i];
+        if (p1 == NULL) {
+            header = p2;
+        }
+        if (p1 == NULL || p2 == NULL) {
+            continue;
+        }
+
+        count++;
+        if (count == 1) {
+            while (p1 != NULL || p2 != NULL) {
+                node = malloc(sizeof(struct ListNode));
+                node->next = NULL;
+                if (p1 == NULL) {
+                    node->val = p2->val;
+                    p2 = p2->next;
+                } else if (p2 == NULL) {
+                    node->val = p1->val;
+                    p1 = p1->next;
+                } else {
+                    if (p1->val < p2->val) {
+                        node->val = p1->val;
+                        p1 = p1->next;
+                    } else {
+                        node->val = p2->val;
+                        p2 = p2->next;
+                    }
+                }
+                if (start == 0) {
+                    header = p = node;
+                    start = 1;
+                } else {
+                    p->next = node;
+                    p = node;
+                }
+            }
+        } else {
+            prev = NULL;
+            while (p1 != NULL || p2 != NULL) {
+                if (p1 == NULL) {
+                    node = malloc(sizeof(struct ListNode));
+                    node->next = NULL;
+                    node->val = p2->val;
+                    if (prev == NULL) {
+                        node->next = header;
+                        header = node;
+                    } else {
+                        prev->next = node;
+                        prev = node;
+                    }
+                    p2 = p2->next;
+                } else if (p2 == NULL) {
+                    break;
+                } else {
+                    if (p1->val < p2->val) {
+                        prev = p1;
+                        p1 = p1->next;
+                    } else {
+                        node = malloc(sizeof(struct ListNode));
+                        node->val = p2->val;
+                        if (prev == NULL) {
+                            node->next = header;
+                            header = node;
+                        } else {
+                            prev->next = node;
+                            node->next = p1;
+                        }
+                        prev = node;
+                        p2 = p2->next;
+                    }
+                }
+            }
+        }
+
+    }
+    return header;
+}
+
+void testMergeKLists() {
+    int a[] = {-1, 1};
+    int b[] = {-3, 1, 4};
+    int c[] = {-2,-1,0,2};
+    int a1[] = {1};
+    int a2[] = {0};
+    struct ListNode *l1 = createList(a, 2);
+    struct ListNode *l2 = createList(b, 3);
+    struct ListNode *l3 = createList(c, 4);
+    struct ListNode *l11 = createList(a1, 1);
+    struct ListNode *l12 = createList(a2, 1);
+    struct ListNode **l = malloc(sizeof(struct ListNode *) * 4);
+    l[0] = l1;l[1] = l2;l[2]=l3;l[3] = l3;
+    //l[0] = l11;
+    //l[1] = l12;
+    printList(mergeKLists(l, 3));
+}