how to merge two sorted array in one sorted array in JavaScript without using sort()

Question

In this program merged two array and then sorted using temp.but this not correct method.because two array are sorted ,so method should be unique i.e. merging of two sorted i

Answer 1

How about something like this?

Since a and b are both sorted we only need to consider the top or first item of each array when adding. Note that this method will modify both a and b during execution, this may not be what you want, in which case you can add this code at the start:

var tempA = a.slice();
var tembB = b.slice();

This will make copies of the array which you can then use instead of a and b in the function below:

function mergeSortedArray(a,b){
    var tempArray = [];
    while(a.length || b.length) {
        if(typeof a[0] === 'undefined') {
            tempArray.push(b[0]);
            b.splice(0,1);
        } else if(a[0] > b[0]){
            tempArray.push(b[0]);
            b.splice(0,1);
        } else {
            tempArray.push(a[0]);
            a.splice(0,1);
        }
    }
    return tempArray;
}
console.log(mergeSortedArray([4,6,7,8], [1,2,3,5,9]));

Without using splice at all, try something like this:

function mergeSortedArray(a,b){
    var tempArray = [];
    var currentPos = {
        a: 0,
        b: 0
    }
    while(currentPos.a < a.length || currentPos.b < b.length) {
        if(typeof a[currentPos.a] === 'undefined') {
            tempArray.push(b[currentPos.b++]);
        } else if(a[currentPos.a] > b[currentPos.b]){
            tempArray.push(b[currentPos.b++]);
        } else {
            tempArray.push(a[currentPos.a++]);
        }
    }
    return tempArray;
}
console.log(mergeSortedArray([1,2,3,5,9],[4,6,7,8]));