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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.top() -- Get the top element.getMin() -- Retrieve the minimum element in the stack.Example: MinStack minStack = new MinStack(); minStack.push(-2); minStack.push(0); minStack.push(-3); minStack.getMin(); --> Returns .. 더보기
Valid Parentheses Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.An input string is valid if:Open brackets must be closed by the same type of brackets.Open brackets must be closed in the correct order.Note that an empty string is also considered valid.Example 1:Input: "()" Output: true Example 2:Input: "()[]{}" Output: true Example 3:Input: "(.. 더보기
Pascal's Triangle Given a non-negative integer numRows, generate the first numRows of Pascal's triangle. In Pascal's triangle, each number is the sum of the two numbers directly above it.Example:Input: 5 Output: [ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1] ] My solution:class Solution: def generate(self, numRows): """ :type numRows: int :rtype: List[List[int]] """ result = list() if numRows > 0: result.append([1.. 더보기

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