Merge Sorted Array

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 nums1and nums2 are m and n respectively.

思路：从后向前合并，这样就不需要额外的存储空间，时间复杂度为O(m+n)也非常好

public class Solution {
public void merge(int[] nums1, int m, int[] nums2, int n) {
int count1 = m-1;
int count2 = n-1;
int count3 = m+n-1;
while(count1>=0 && count2>=0) {
if(nums1[count1]>=nums2[count2]) {
nums1[count3] = nums1[count1];
count3--;
count1--;
} else {

nums1[count3] = nums2[count2];
count3--;
count2--;
}
}
if(count2<0) {
return;
} else{
for(int i=0;i<=count2;i++) {
nums1[i] = nums2[i];
}
return;
}
}

}