Sort Colors Two Pointer Dutch Flag in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the left pointer to the start of the array.

DSA C

int left = [1];

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

A1

B0

C-1

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Starting left pointer at 1 or negative index.

The left pointer should start at index 0 to begin sorting from the start.

2fill in blank

medium

Complete the code to initialize the right pointer to the end of the array.

DSA C

int right = [1] - 1;

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

An

Blength

Csize

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or length without subtracting 1.

The right pointer should start at the last index, which is n - 1.

3fill in blank

hard

Fix the error in the while loop condition to process elements correctly.

DSA C

while ([1]) {

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

Ai < right

Bleft <= right

Ci < left

Di <= right

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of <= causing last element to be skipped.

The loop should continue while i is less than or equal to right to cover all elements.

4fill in blank

hard

Fill both blanks to swap elements and update pointers correctly when nums[i] is 0.

DSA C

if (nums[i] == 0) {
    swap(nums, i, [1]);
    i++;
    [2]++;
}

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

Aleft

Bright

Ci

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping with right pointer or incrementing wrong variables.

Swap with left pointer and then increment both i and left to move forward.

5fill in blank

hard

Fill all three blanks to swap elements and update pointers correctly when nums[i] is 2.

DSA C

else if (nums[i] == 2) {
    swap(nums, i, [1]);
    [2]--;
    [3] = [3];
}

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

Aleft

Bright

Ci

Attempts:

3 left

💡 Hint

Common Mistakes

Incrementing i after swapping with right pointer.

Swap with right pointer, decrement right, and keep i same to recheck swapped element.