Code Challenges

Get better at coding with practice problems.

Coding Challenges

Select a problem, write code, run test cases, and submit your solution.

Stack Topological Sort Simulation

Intermediate

Implement the `minStackFinalMinimum` method that simulates stack operations and returns the final minimum value.

Stack Topological Sort Simulation

Intermediate

Implement the `evaluateRpnExpression` method that evaluates an arithmetic expression written in Reverse Polish Notation.

Stack Topological Sort Simulation

Proficient

Implement the `removeDuplicateLettersSmallest` method that removes duplicate letters and returns the smallest possible result.

Stack Topological Sort Simulation

Proficient

Implement the `longestValidParenthesesLength` method that returns the length of the longest valid parentheses substring.

Stack Topological Sort Simulation

Guru

Implement the `basicCalculatorPlusMinus` method that evaluates an expression containing plus and minus operations.

Stack Topological Sort Simulation

Intermediate

Implement the `onlineStockSpanLast` method that returns the latest stock span value from the price stream.

Stack Topological Sort Simulation

Intermediate

Implement the `removeKDigitsMinimum` method that removes k digits to form the smallest possible number.

Stack Topological Sort Simulation

Intermediate

Implement the `asteroidCollisionSurvivors` method that returns the asteroids that remain after all collisions are resolved.

Stack Topological Sort Simulation

Intermediate

Implement the `decodeEncodedStringSimple` method that decodes a bracketed encoded string pattern.

Stack Topological Sort Simulation

Intermediate

Implement the `minRemoveValidParentheses` method that removes the minimum invalid parentheses to make the text valid.

Stack Topological Sort Simulation

Proficient

Implement the `largestRectangleHistogram` method that returns the largest rectangle area possible in a histogram.

Stack Topological Sort Simulation

Intermediate

Implement the `dailyTemperaturesWait` method that returns how many days must be waited for a warmer temperature.

Stack Topological Sort Simulation

Learner

Implement the `nextGreaterElementArray` method that returns the next greater value for each array element.

Stack Topological Sort Simulation

Learner

Implement the `validParenthesesMixed` method that checks whether mixed parentheses are correctly balanced.

Decision Making Stack Simulation

Learner

Implement the `isValidBracketPairString` method that checks whether a bracket string has properly matched and ordered brackets.

String Manipulation String Stack Simulation

Learner

Implement the `removeAdjacentDuplicates` method that removes adjacent duplicate characters using stack-style processing.

Intermediate

Implement the method `isBalancedBrackets` that checks whether brackets are correctly nested.