Leetcode[88] Merge Sorted Array
06 Nov 2015###Task Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.
Note: You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. The number of elements initialized in nums1 and nums2 are m and n respectively.
###Python
class Solution(object):
def merge(self, nums1, m, nums2, n):
"""
:type nums1: List[int]
:type m: int
:type nums2: List[int]
:type n: int
:rtype: void Do not return anything, modify nums1 in-place instead.
"""
if nums1 == None or nums2 == None:
return
if len(nums1) == 0 or len(nums2) == 0:
return
while m > 0 and n > 0:
if nums1[m - 1] > nums2[n - 1]:
nums1[m + n - 1] = nums1[m - 1]
m -= 1
else:
nums1[m + n - 1] = nums2[n - 1]
n -= 1
while n > 0:
nums1[n - 1] = nums2[n - 1]
n -= 1
###Java
public class Solution {
public void merge(int[] nums1, int m, int[] nums2, int n) {
//this is indeed simple TAT why I cannot figure this out
if (nums1 == null || nums2 == null || nums1.length < m || nums2.length < n) {
return ;
}
int i = m - 1;
int j = n - 1;
int pos = m + n - 1;
while (i >= 0 && j >= 0) {
if (nums1[i] > nums2[j]) {
nums1[pos--] = nums1[i--];
} else {
nums1[pos--] = nums2[j--];
}
}
while (i >= 0) {
nums1[pos--] = nums1[i--];
}
while (j >= 0) {
nums1[pos--] = nums2[j--];
}
return;
}
}
###Points
- Start from tail
- Pay attention to the number of elements and subscription
- O(m + n)