Non Overlapping Intervals Minimum Removal in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to sort intervals by their end time.

DSA C

int compare(const void *a, const void *b) {
    int *intervalA = *(int **)a;
    int *intervalB = *(int **)b;
    return intervalA[[1]] - intervalB[[1]];
}

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A-1

B0

C1

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Sorting by start time instead of end time.

Using wrong index for end time.

We sort intervals by their end time, which is at index 1 in each interval array.

2fill in blank

medium

Complete the code to initialize the count of non-overlapping intervals.

DSA C

int count = 1;
int prev_end = intervals[0][[1]];

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A1

B2

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using start time instead of end time.

Initializing count to 0 instead of 1.

We start with the first interval's end time at index 1 to compare with others.

3fill in blank

hard

Fix the error in the condition to check if intervals overlap.

DSA C

for (int i = 1; i < intervalsSize; i++) {
    if (intervals[i][0] >= [1]) {
        count++;
        prev_end = intervals[i][1];
    }
}

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Aintervals[i][1]

Bcount

Cintervals[i][0]

Dprev_end

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing start time with start time.

Using wrong variable in condition.

We compare the current interval's start time with the previous interval's end time to check overlap.

4fill in blank

hard

Fill both blanks to calculate the minimum number of intervals to remove.

DSA C

int minRemoval = [1] - [2];
return minRemoval;

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AintervalsSize

Bcount

Cprev_end

Di

Attempts:

3 left

💡 Hint

Common Mistakes

Subtracting wrong variables.

Returning count instead of minimum removals.

Minimum removals = total intervals - count of non-overlapping intervals.

5fill in blank

hard

Fill all three blanks to complete the function for minimum removals.

DSA C

int eraseOverlapIntervals(int** intervals, int intervalsSize, int* intervalsColSize) {
    qsort(intervals, intervalsSize, sizeof(int*), [1]);
    int count = 1;
    int prev_end = intervals[0][[2]];
    for (int i = 1; i < intervalsSize; i++) {
        if (intervals[i][0] >= [3]) {
            count++;
            prev_end = intervals[i][1];
        }
    }
    return intervalsSize - count;
}

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Acompare

B1

Cprev_end

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong function name in qsort.

Using wrong indices for start/end times.

Incorrect overlap condition.

We use compare function for sorting, index 1 for end time, and prev_end to check overlap.