LeetCode OJ - Merge Sorted Array & Merge Two Sorted Lists

Merge Sorted Array

 

Given two sorted integer arrays A and B, merge B into A as one sorted array.

Note:

You may assume that A has enough space (size that is greater or equal to m + n) to hold additional elements from B. The number of elements initialized in A and B are m andn respectively.

分析：归并基本操作

class Solution {
public:
void merge(int A[], int m, int B[], int n) {
int i = m - 1, j = n - 1;
int x = m + n - 1;
while(i >= 0 && j >= 0) {
if(A[i] > B[j]) {
A[x--] = A[i--];
} else {
A[x--] = B[j--];
}
}

while(i >= 0) {
A[x--] = A[i--];
}

while(j >= 0) {
A[x--] = B[j--];
}
}
};

Merge Two Sorted Lists

 

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two
lists.

/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/

class Solution {
public:
ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
ListNode dummy(0);
ListNode *head = &dummy;

while(l1 && l2) {
if(l1->val < l2->val) {
head->next = l1;
l1 = l1->next;
head = head->next;
} else {
head->next = l2;
l2 = l2->next;
head = head->next;
}
}

while(l1) {
head->next = l1;
l1 = l1->next;
head = head->next;
}

while(l2) {
head->next = l2;
l2 = l2->next;
head = head->next;
}

return dummy.next;
}
};