# Merge Two Sorted Arrays

ID: 6; easy

## Solution 1 (Java)

``````public class Solution {
/**
* @param A: sorted integer array A
* @param B: sorted integer array B
* @return: A new sorted integer array
*/
public int[] mergeSortedArray(int[] A, int[] B) {
if (A == null) return B;
if (B == null) return A;

int[] ans = new int[A.length + B.length];
int i = 0, j = 0, k = 0;
while (i < A.length && j < B.length) {
ans[k++] = A[i] < B[j] ? A[i++] : B[j++];
}
while (i < A.length) {
ans[k++] = A[i++];
}
while (j < B.length) {
ans[k++] = B[j++];
}

return ans;
}
}``````

## Solution 2 (Java)

``````public class Solution {
/**
* @param A: sorted integer array A
* @param B: sorted integer array B
* @return: A new sorted integer array
*/
public int[] mergeSortedArray(int[] A, int[] B) {
if (A == null || A.length == 0) return B;
if (B == null || B.length == 0) return A;

int lenA = A.length;
int lenB = B.length;

int[] res = new int[lenA + lenB];
int i = 0, j = 0;
for (int k = 0; k < lenA + lenB; k++) {
if (i < lenA && (j >= lenB || A[i] <= B[j])) {
res[k] = A[i++];
} else {
res[k] = B[j++];
}
}

return res;
}
}``````

## Solution 3 (Java)

``````public class Solution {
/**
* @param A: sorted integer array A
* @param B: sorted integer array B
* @return: A new sorted integer array
*/
public int[] mergeSortedArray(int[] A, int[] B) {
if (A == null) return B;
if (B == null) return A;

int[] res = new int[A.length + B.length];
int i = 0, k = 0;
for (int j = 0; j < B.length; j++) {
int pos = binarySearch(A, B[j]);
while (i < pos) {
res[k++] = A[i++];
}
res[k++] = B[j];
}
while (i < A.length) {
res[k++] = A[i++];
}
return res;
}

private int binarySearch(int[] A, int target) {
int left = 0;
int right = A.length - 1;
while (left <= right) {
int mid = left + (right - left) / 2;
if(A[mid] == target) {
return mid;
} else if(target < A[mid]){
right = mid - 1;
} else{
left = mid + 1;
}
}
return left;
}
}``````

### Notes

• This solution is to handle the challenge: How can you optimize your algorithm if one array is very large and the other is very small?

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