ADVANCED DATA STRUCTURES PROGRAM • LEVEL 21 — PLACEMENT-ORIENTED STRUCTURES

Merge K Sorted Streams for an Interview

Learn how to merge k sorted streams for an interview using a clear C program.

AdvancedInterview patternRange and stream queries

PROBLEM UNDERSTANDING

Input and expected output

Sample input

No input required

Sample output

1 2 3 4 5 6 7 8 9

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

int main(void)
{
    int streams[3][3]={{1,4,7},{2,5,8},{3,6,9}},position[3]={0};for(int out=0;out<9;out++){int best=-1;for(int i=0;i<3;i++)if(position[i]<3&&(best<0||streams[i][position[i]]<streams[best][position[best]]))best=i;printf("%d%c",streams[best][position[best]++],out==8?'\n':' ');}return 0;
}

CURRENT STEP

Select Start to walk through the important lines.

SELECTED LINE

No line selected

EXPECTED OUTPUT FOR THE SAMPLE

1 2 3 4 5 6 7 8 9

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Maintain one current candidate per stream and advance only the stream whose value is emitted.
Display the computed result.

Maintain one current candidate per stream and advance only the stream whose value is emitted.

EFFICIENCY

Time and space complexity

Time complexity

O(total log k) with a heap

Auxiliary space

O(k)

DEBUGGING CHECKLIST

Common mistakes

Check this

Use the correct format specifier for every variable.

Check this

Initialize variables before using their values.

Check this

Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.