Merge sort - Programmers Heaven

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# Merge sort

Posts: 3Member
Hi all, i'm new to algorithms and to this forum but was wondering if anyone has an algorithm which uses a merge sort to sort three sorted sequences into one?

Any help would be much appreciated. Thanks in advance

• Posts: 6,349Member
: Hi all, i'm new to algorithms and to this forum but was wondering if
: anyone has an algorithm which uses a merge sort to sort three sorted
: sequences into one?
:
: Any help would be much appreciated. Thanks in advance

Here is a simplified algorithm to merge 3 sorted lists. It is not the merge sort, because that's a full sorting algorithm, not just a way to merge sorted lists.
[code]
outList MergeLists (inListArray) {

// Loop until all lists are empty

while (length inListArray > 0) {
int small = 0;

// First find smallest item in all the lists

for (i = 0 ; i < length inListArray; i++) {
if (inListArray[i][0] < inListArray[small][0])
small = i;
}

// Then add that item into the result list and remove it from the source list

move inListArray[small][0] to outList

// Finally check if that list becomes empty

if (length inListArray[small] = 0) {
remove inListArray[small] from inListArray
}
}
}
[/code]
This code runs in O(n) time, where n is the number of total items.
• Posts: 3Member
Thank you very much for your help with this! As I say i'm very new to algorithms and am trying to answer a few questions so am just about to make another post and would be great if you could help!

Many thanks