Making Apps More Accessible

* The article source is from Udacity Nanodegree Program- Become an Android Developer *

Accessibility refers to the design of products, devices, services, or environments for people who experience disabilities. Android provides accessibility features like

  • TalkBack: It uses spoken feedback to describe the results of actions such as launching an app, and events such as notifications.
  • Explore by Touch which is a system feature that works with TalkBack, allowing you to touch your device’s screen and hear what’s under your finger via spoken feedback. This feature is helpful to users with low vision.
  • Accessibility settings that let you modify your device’s display and sound options, such as increasing the text size, changing the speed at which text is spoken, and more. and more.

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leetcode- Rotate Image


Given input matrix = 

rotate the input matrix in-place such that it becomes:
  • (x, y), the affected point is
    (y, n – x – 1), (n – x – 1, n – y – 1), (n – y – 1, x),  “n” is the size of the matrix.
    The rotate function=
    (x, y) -> (y, n – x – 1) -> (n – x – 1, n – y – 1) -> (n – y – 1, x) -> (x, y).
  • For the i th line, we start from (i, i) ( !! in for loop  j = i ) , and ends at (i, n – 2 – i) 
  • We only need process half of them. n/2

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leetcode- Valid Sudoku
In a 9 * 9 matrix, check if each numbers (0-9) doesn’t repeat in each row, col and 3 * 3 matrix.

  • use a HashSet or array to check if the number is used.
  • check 3*3 squart –> board [ i + k/3 ][ j + k%3 ] (i, j are 9*9 board index, k is the check board (0-9) index)
  • if(digit > 9 || digit < 1 || check[digit -1]), check digit is valid first then check if the number is used

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LeetCode – Plus One

Given a non-negative integer represented as a non-empty array of digits, plus one to the integer. You may assume the integer do not contain any leading zero, except the number 0 itself. The digits are stored such that the most significant digit is at the head of the list.

For example:
int[] nums = {1,2,3,4};
int[] result = plusOne(nums);
the digits are in the result array are {1,2,3,5};

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