kth 402. Remove K Digits Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible.Note: The length of num is less than 10002

Rectangle 85. Maximal Rectangle Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing only 1's and return its area.Example: Input: [ ["1","0","1","0","0"], ["1","0","1","1","1"

stack Min Stack Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.push(x) -- Push element x onto stack.pop() -- Removes the element on top of the

stack 84. Largest Rectangle in Histogram Given n non-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the histogram. Above is a histogram where width of