# [leetcode] 88. Merge Sorted Array

boricat·2021년 11월 24일
0

## leetcode

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You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and nums2 respectively.

Merge nums1 and nums2 into a single array sorted in non-decreasing order.

The final sorted array should not be returned by the function, but instead be stored inside the array nums1. To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged, and the last n elements are set to 0 and should be ignored. nums2 has a length of n.

Example 1:

Input: nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3
Output: [1,2,2,3,5,6]
Explanation: The arrays we are merging are [1,2,3] and [2,5,6].
The result of the merge is [1,2,2,3,5,6] with the underlined elements coming from nums1.
Example 2:

Input: nums1 = [1], m = 1, nums2 = [], n = 0
Output: [1]
Explanation: The arrays we are merging are [1] and [].
The result of the merge is [1].
Example 3:

Input: nums1 = [0], m = 0, nums2 = [1], n = 1
Output: [1]
Explanation: The arrays we are merging are [] and [1].
The result of the merge is [1].
Note that because m = 0, there are no elements in nums1. The 0 is only there to ensure the merge result can fit in nums1.

Constraints:

nums1.length == m + n
nums2.length == n
0 <= m, n <= 200
1 <= m + n <= 200
-109 <= nums1[i], nums2[j] <= 109

### sol1

class Solution {
public void merge(int[] nums1, int m, int[] nums2, int n) {

if(nums1==null || nums2 == null || m<0 || n<0 || nums1.length < m+n || nums2.length < n){

throw new IllegalArgumentException("Invaild Input");

}

if(n == 0){
return;
}

int k = m + n - 1;
m--;
n--;

while(m >= 0 && n>= 0){
if(nums1[m] >= nums2[n]){
nums1[k--] = nums1[m--];

} else {

nums1[k--] = nums2[n--];
}

}

while(n>=0){
nums1[k--] = nums2[n--];

}

}
}

### sol2

        int i = m-1;
int j = n-1;
int k = m + n - 1;

while(i > -1 && j > -1){
if(nums1[i] > nums2[j]){
nums1[k] = nums1[i];
i--;
}else{
nums1[k] = nums2[j];
j--;
}
k--;
}

while(i > -1){
nums1[k] = nums1[i];
i--;
k--;
}

while(j > -1){
nums1[k] = nums2[j];
j--;
k--;
}
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