Next Permutation of Array in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find the first index from the end where the array value is less than the next value.

DSA C

int i = n - 2;
while (i >= 0 && nums[i] [1]= nums[i + 1]) {
    i--;
}

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

A>

B<

C>=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' instead of '>=' causes the loop to stop too early.

Using '>' misses the case when nums[i] equals nums[i+1].

We look for the first index i from the right where nums[i] is less than nums[i+1], so we continue while nums[i] >= nums[i+1].

2fill in blank

medium

Complete the code to find the first index from the end where the array value is greater than nums[i].

DSA C

int j = n - 1;
while (j >= 0 && nums[j] [1]= nums[i]) {
    j--;
}

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

A>=

B<

C>

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '<=' causes skipping equal values.

Using '>=' causes the loop to stop too late.

We want to find the first index j from the right where nums[j] is greater than nums[i], so we continue while nums[j] <= nums[i].

3fill in blank

hard

Fix the error in swapping nums[i] and nums[j].

DSA C

int temp = nums[i];
nums[i] = nums[[1]];
nums[j] = temp;

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Ai + 1

Bj

Ci

Dj - 1

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping with nums[i] again causes no change.

Using wrong indices causes incorrect swap.

To swap nums[i] and nums[j], we assign nums[i] = nums[j], then nums[j] = temp.

4fill in blank

hard

Fill both blanks to reverse the subarray from i+1 to end.

DSA C

int start = i + 1;
int end = n - 1;
while (start [1] end) {
    int temp = nums[start];
    nums[start] = nums[end];
    nums[end] = temp;
    start[2];
    end--;
}

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

A<

B<=

C++

D--

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' causes swapping the middle element twice.

Using '--' on start moves it backward incorrectly.

We reverse while start < end, and increment start with start++ each loop.

5fill in blank

hard

Fill all three blanks to complete the next permutation function.

DSA C

void nextPermutation(int* nums, int n) {
    int i = n - 2;
    while (i >= 0 && nums[i] [1]= nums[i + 1]) {
        i--;
    }
    if (i >= 0) {
        int j = n - 1;
        while (j >= 0 && nums[j] [2]= nums[i]) {
            j--;
        }
        int temp = nums[i];
        nums[i] = nums[j];
        nums[j] = temp;
    }
    int start = i + 1;
    int end = n - 1;
    while (start [3] end) {
        int temp = nums[start];
        nums[start] = nums[end];
        nums[end] = temp;
        start++;
        end--;
    }
}

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

A>=

B<=

C<

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up comparison operators causes incorrect next permutation.

Using wrong loop conditions leads to infinite loops or wrong output.

The blanks correspond to the conditions and loop control: i moves left while nums[i]>=nums[i+1], j moves left while nums[j]<=nums[i], and reversing while start