DATA STRUCTURES PROGRAM • ARRAY TECHNIQUES

Merge Overlapping Intervals

Learn how to merge overlapping intervals using a clear C program.

AdvancedIntervalsSortingGreedy merge

PROBLEM UNDERSTANDING

Input and expected output

Sample input

No input required

Sample output

[1,6] [8,10] [15,18]

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

struct Interval { int start; int end; };

int main(void)
{
    struct Interval intervals[] = {{1, 3}, {2, 6}, {8, 10}, {15, 18}};
    int count = 4, write = 0;
    for (int index = 1; index < count; index++) {
        if (intervals[index].start <= intervals[write].end) {
            if (intervals[index].end > intervals[write].end) intervals[write].end = intervals[index].end;
        } else intervals[++write] = intervals[index];
    }
    for (int index = 0; index <= write; index++)
        printf("[%d,%d] ", intervals[index].start, intervals[index].end);
    putchar('\n');
    return 0;
}

CURRENT STEP

Select Start to walk through the important lines.

SELECTED LINE

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EXPECTED OUTPUT FOR THE SAMPLE

[1,6] [8,10] [15,18]

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
After sorting by start time, extend the current interval or begin a new merged interval.
Display the computed result.

After sorting by start time, extend the current interval or begin a new merged interval.

EFFICIENCY

Time and space complexity

Time complexity

O(n log n) including sorting

Auxiliary space

O(1)

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.