Floor and Ceil in Sorted Array in DSA C++ - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find the floor value index in a sorted array.

DSA C++

int floorIndex(const vector<int>& arr, int x) {
    int low = 0, high = arr.size() - 1;
    int result = -1;
    while (low <= high) {
        int mid = low + (high - low) / 2;
        if (arr[mid] == x) {
            return mid;
        } else if (arr[mid] [1] x) {
            result = mid;
            low = mid + 1;
        } else {
            high = mid - 1;
        }
    }
    return result;
}

Drag options to blanks, or click blank then click option'

A>

B>=

C<

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '<=' causes missing correct floor values.

Not updating result when arr[mid] <= x.

We want to find the floor, so if arr[mid] is less than or equal to x, we update result and move right.

2fill in blank

medium

Complete the code to find the ceil value index in a sorted array.

DSA C++

int ceilIndex(const vector<int>& arr, int x) {
    int low = 0, high = arr.size() - 1;
    int result = -1;
    while (low <= high) {
        int mid = low + (high - low) / 2;
        if (arr[mid] == x) {
            return mid;
        } else if (arr[mid] [1] x) {
            result = mid;
            high = mid - 1;
        } else {
            low = mid + 1;
        }
    }
    return result;
}

Drag options to blanks, or click blank then click option'

A>

B>=

C<=

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' causes wrong ceil index.

Not updating result when arr[mid] >= x.

For ceil, if arr[mid] is greater than or equal to x, we update result and move left. Here, '>' is used to check if arr[mid] is strictly greater than x.

3fill in blank

hard

Fix the error in the binary search condition to correctly find the floor index.

DSA C++

int floorIndex(const vector<int>& arr, int x) {
    int low = 0, high = arr.size() - 1;
    int result = -1;
    while (low <= high) {
        int mid = low + (high - low) / 2;
        if (arr[mid] == x) {
            return mid;
        } else if (arr[mid] [1] x) {
            result = mid;
            low = mid + 1;
        } else {
            high = mid - 1;
        }
    }
    return result;
}

Drag options to blanks, or click blank then click option'

A<=

B>

C<

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' causes skipping valid floor elements.

Not updating result when arr[mid] <= x.

The condition must be arr[mid] <= x to find the floor correctly.

4fill in blank

hard

Fill both blanks to complete the code that finds floor and ceil indices in a sorted array.

DSA C++

pair<int, int> floorAndCeil(const vector<int>& arr, int x) {
    int low = 0, high = arr.size() - 1;
    int floor = -1, ceil = -1;
    while (low <= high) {
        int mid = low + (high - low) / 2;
        if (arr[mid] == x) {
            floor = mid;
            ceil = mid;
            break;
        } else if (arr[mid] [1] x) {
            floor = mid;
            low = mid + 1;
        } else {
            ceil = mid;
            high = mid - 1;
        }
    }
    return {floor, ceil};
}

Drag options to blanks, or click blank then click option'

A<=

B>

C<

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping floor and ceil conditions.

Not updating floor or ceil indices properly.

For floor, use '<=' to move right and update floor. For ceil, use '>' to move left and update ceil.

5fill in blank

hard

Fill all three blanks to complete the code that returns a map of floor and ceil values for each query in a sorted array.

DSA C++

map<int, pair<int, int>> floorAndCeilForQueries(const vector<int>& arr, const vector<int>& queries) {
    map<int, pair<int, int>> result;
    for (int q : queries) {
        int low = 0, high = arr.size() - 1;
        int floor = -1, ceil = -1;
        while (low <= high) {
            int mid = low + (high - low) / 2;
            if (arr[mid] == q) {
                floor = mid;
                ceil = mid;
                break;
            } else if (arr[mid] [1] q) {
                floor = mid;
                low = mid + 1;
            } else {
                ceil = mid;
                high = mid - 1;
            }
        }
        result[q] = {arr[2], arr[3];
    }
    return result;
}

Drag options to blanks, or click blank then click option'

A<=

B[floor]

C[ceil]

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operators.

Accessing arr with wrong indices or missing brackets.

Use '<=' for floor condition. Use floor and ceil indices to access arr elements for values.