Merge Overlapping Intervals in DSA C - Build from Scratch

Merge Overlapping Intervals

📖 Scenario: You are working on a calendar app that manages meeting times. Sometimes meetings overlap, and you want to combine those overlapping meetings into one longer meeting to avoid confusion.

🎯 Goal: Build a program that merges overlapping intervals from a list of meeting times and prints the merged intervals.

📋 What You'll Learn

Create an array of intervals with exact values

Add a variable to store the number of intervals

Implement the logic to merge overlapping intervals

Print the merged intervals in the format: [start, end]

💡 Why This Matters

🌍 Real World

Merging overlapping intervals is useful in calendar apps, booking systems, and timeline visualizations to avoid conflicts and show clear schedules.

💼 Career

Understanding interval merging helps in software development roles involving scheduling, data processing, and algorithm design.

1

Create the initial intervals array

Create an array called intervals of type int[][2] with these exact intervals: {1, 3}, {2, 6}, {8, 10}, {15, 18}.

DSA C

int intervals[][2] = {
    // Your code here
};

Hint

Use curly braces to define each interval inside the array.

2

Add the number of intervals variable

Create an int variable called n and set it to 4, the number of intervals in intervals.

DSA C

int intervals[][2] = {{1, 3}, {2, 6}, {8, 10}, {15, 18}};
// Your code here

Hint

Count how many intervals are in the array and assign that number to n.

3

Implement merging logic

Write code to merge overlapping intervals from intervals using n. Store merged intervals in merged array and keep count in mergedCount. Use a simple sorting and merging approach.

DSA C

int intervals[][2] = {{1, 3}, {2, 6}, {8, 10}, {15, 18}};
int n = 4;
// Your code here

Hint

Sort intervals by start time, then merge by comparing current interval start with last merged interval end.

4

Print merged intervals

Print each merged interval from merged array using mergedCount. Format each interval as [start, end] on its own line.

DSA C

int intervals[][2] = {{1, 3}, {2, 6}, {8, 10}, {15, 18}};
int n = 4;

// Simple bubble sort by start time
for (int i = 0; i  intervals[j + 1][0]) {
            int temp0 = intervals[j][0];
            int temp1 = intervals[j][1];
            intervals[j][0] = intervals[j + 1][0];
            intervals[j][1] = intervals[j + 1][1];
            intervals[j + 1][0] = temp0;
            intervals[j + 1][1] = temp1;
        }
    }
}

int merged[10][2];
int mergedCount = 0;

merged[0][0] = intervals[0][0];
merged[0][1] = intervals[0][1];
mergedCount = 1;

for (int i = 1; i  merged[mergedCount - 1][1]) {
            merged[mergedCount - 1][1] = intervals[i][1];
        }
    } else {
        merged[mergedCount][0] = intervals[i][0];
        merged[mergedCount][1] = intervals[i][1];
        mergedCount++;
    }
}
// Your code here

Hint

Use a for loop to print each merged interval with printf.