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SBI Coding Questions

Overview

Practice SBI coding questions in the style students report for online assessments and technical interviews. Focus areas: Aptitude, reasoning, GA, English. Languages commonly allowed: Specialist tech cadres differ.

SBI coding pattern

Item Typical expectation
Problems 1-3 coding tasks depending on drive
Skills Aptitude, reasoning, GA, English
Languages Specialist tech cadres differ (use what the assessment email lists)
What matters Correctness first, then speed and clear code

Practice problems

Question 1: linked list cycle

Coding Q1: Linked list cycle

Problem: Given the head of a linked list, return true if there is a cycle and false otherwise.

Approach: Floyd’s tortoise and hare: move one pointer one step and another two steps. If they meet, a cycle exists. If the fast pointer hits null, there is no cycle.

Complexity: O(n) time, O(1) space

SBI tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.

Question 2: binary tree level order

Coding Q2: Binary tree level order

Problem: Given the root of a binary tree, return the level-order traversal (breadth-first) as a list of levels.

Approach: Use a queue. For each level, drain the current queue size, collect values, and enqueue children for the next level.

Complexity: O(n) time, O(n) space

SBI tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.

Question 3: coin change

Coding Q3: Coin change (min coins)

Problem: Given coin denominations and an amount, return the fewest coins needed to make that amount, or -1 if it is impossible.

Approach: Unbounded knapsack DP: let dp[x] be the minimum coins for amount x. For each coin, update dp[c..amount]. Initialize dp[0] = 0 and the rest to a large sentinel.

Complexity: O(amount × coins)

SBI tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.

Coding Q4: Binary search

Problem: Given a sorted array of distinct integers and a target, return the index of target or -1 if missing.

Approach: Maintain lo/hi. Compare mid with target and shrink the half that cannot contain it. Careful with overflow-free mid and empty arrays.

Complexity: O(log n) time

SBI tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.

Question 5: move zeros

Coding Q5: Move zeros

Problem: Move all zeros in an array to the end while keeping the relative order of non-zero elements.

Approach: Two pointers: write non-zeros toward the front, then fill the remainder with zeros. Or swap zeros as you scan.

Complexity: O(n) time, O(1) space

SBI tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.

Question 6: rotate array

Coding Q6: Rotate array

Problem: Rotate an array to the right by k steps. Example: [1,2,3,4,5,6,7], k = 3 → [5,6,7,1,2,3,4].

Approach: Normalize k %= n. Reverse the whole array, reverse the first k elements, then reverse the rest. That yields the rotation in place.

Complexity: O(n) time, O(1) space

SBI tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.

Question 7: first unique character

Coding Q7: First unique character

Problem: Find the first non-repeating character in a string and return its index, or -1 if none exists.

Approach: Count frequencies in one pass (hash map or array of 26 for lowercase). Second pass returns the first index with count 1.

Complexity: O(n) time

SBI tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.

Question 8: stack with min

Coding Q8: Stack with min

Problem: Design a stack that supports push, pop, top, and getMin in average O(1) time.

Approach: Keep a parallel min-stack (or store pairs). When pushing, also push the new minimum. When popping, pop both stacks.

Complexity: O(1) per operation amortized

SBI tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.

Question 9: maximum subarray sum

Coding Q9: Maximum subarray sum (Kadane)

Problem: Given an integer array, find the contiguous subarray with the largest sum and return that sum. Example: [-2,1,-3,4,-1,2,1,-5,4] → 6 (from [4,-1,2,1]).

Approach: Keep a running sum. If the running sum drops below 0, reset it to 0 before taking the next element (or track the best ending-here value). Track the global maximum as you scan once from left to right.

Complexity: O(n) time, O(1) extra space

SBI tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.

Question 10: reverse a string in place

Coding Q10: Reverse a string in place

Problem: Given a mutable character array representing a string, reverse it in place without allocating another array of the same size.

Approach: Use two pointers at the start and end. Swap characters, then move inward until the pointers meet. Watch empty and single-character inputs.

Complexity: O(n) time, O(1) extra space

SBI tip: Restate the problem, sketch a brute-force idea, then tighten it. Call out edge cases (empty input, single element, overflow) before you write code.

Pattern drill plan (2 weeks)

Day Drill
Mon Arrays + hashing (2 problems)
Tue Two pointers / sliding window
Wed Stacks / strings
Thu Trees or graphs basics
Fri Timed mock (1-2 problems)
Sat Re-solve misses cold
Sun Explain your project out loud + rest

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