Merge two arrays alternately
Medium
Java
Java Arrays
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Problem Statement
Task: merge a and b alternately into a new array. Extra tail should be appended at end.
Input Format
An integer n (size of array a)
Then n integers
An integer m (size of array b)
Then m integers
Then n integers
An integer m (size of array b)
Then m integers
Output Format
A new array formed by merging a and b alternately.
If one array finishes early, append remaining elements of the other.
If one array finishes early, append remaining elements of the other.
Example
3 1 2 3 5 10 20 30 40 50
[1, 10, 2, 20, 3, 30, 40, 50]
Constraints
• n ≥ 0, m ≥ 0
• Must create a new array
• Must create a new array
Concept Explanation
We take one element from a, then one from b,
continue alternately.
If one array ends, add remaining elements of the other.
continue alternately.
If one array ends, add remaining elements of the other.
Step-by-Step Explanation
1.Read arrays a and b.
2.Create new array of size n + m.
3.Initialize indices: i = 0, j = 0, k = 0.
4.While both arrays have elements:
• Add a[i] to result, increment i, k.
• Add b[j] to result, increment j, k.
5.While i < n:
• Add remaining elements of a.
6.While j < m:
• Add remaining elements of b.
7.Return the new array.
2.Create new array of size n + m.
3.Initialize indices: i = 0, j = 0, k = 0.
4.While both arrays have elements:
• Add a[i] to result, increment i, k.
• Add b[j] to result, increment j, k.
5.While i < n:
• Add remaining elements of a.
6.While j < m:
• Add remaining elements of b.
7.Return the new array.
Concept Explanation
We take one element from a, then one from b,
continue alternately.
If one array ends, add remaining elements of the other.
continue alternately.
If one array ends, add remaining elements of the other.
Step-by-Step Explanation
1.Read arrays a and b.
2.Create new array of size n + m.
3.Initialize indices: i = 0, j = 0, k = 0.
4.While both arrays have elements:
• Add a[i] to result, increment i, k.
• Add b[j] to result, increment j, k.
5.While i < n:
• Add remaining elements of a.
6.While j < m:
• Add remaining elements of b.
7.Return the new array.
2.Create new array of size n + m.
3.Initialize indices: i = 0, j = 0, k = 0.
4.While both arrays have elements:
• Add a[i] to result, increment i, k.
• Add b[j] to result, increment j, k.
5.While i < n:
• Add remaining elements of a.
6.While j < m:
• Add remaining elements of b.
7.Return the new array.
Input / Output Format
Input Format
An integer n (size of array a)
Then n integers
An integer m (size of array b)
Then m integers
Then n integers
An integer m (size of array b)
Then m integers
Output Format
A new array formed by merging a and b alternately.
If one array finishes early, append remaining elements of the other.
If one array finishes early, append remaining elements of the other.
Constraints
• n ≥ 0, m ≥ 0
• Must create a new array
• Must create a new array
Examples
Input:
3
1 2 3
5
10 20 30 40 50
Output:
[1, 10, 2, 20, 3, 30, 40, 50]
Example Solution (Public)
static int[] mergeAlternate(int[] a,int[] b){int[] r=new int[a.length+b.length];int i=0,j=0,k=0;while(i<a.length||j<b.length){if(i<a.length) r[k++]=a[i++];if(j<b.length) r[k++]=b[j++];}return r;}
Official Solution Code
static int[] mergeAlternate(int[] a,int[] b){int[] r=new int[a.length+b.length];int i=0,j=0,k=0;while(i<a.length||j<b.length){if(i<a.length) r[k++]=a[i++];if(j<b.length) r[k++]=b[j++];}return r;}
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