虽然我是程序员，但这里只介绍人类的思维方法。
这个方法我是从这里看到的：
https://www.learn-sudoku.com/visual-elimination.html
Most people try to solve Sudoku puzzles by picking a random empty cell and trying to figure out what goes in it. Unless you get lucky, this ends up being frustrating and tedious.
"Visual Elimination" is sort of the opposite of that. Instead of focusing on a particular cell, you focus on a number, and try to figure out the nine places it goes.
刚开始，大多数人可能随意选择一个空的格子，开始尝试看看什么数字可以填进去。 除非你运气好，否则，你最终可能会很沮丧。
视觉消除法（Visual Elimination）是一个反向的方法。 你聚焦在数字上，而不是空格。
That’s right – every number goes into every Sudoku puzzle exactly nine times. No more, no less. Each puzzle has nine 1s, nine 2s, nine 3s, etc.
Ok, now train yourself to look at just the larger squares in the puzzle. Think of the puzzle as a tic-tac-toe game, or a "Brady Bunch" grid (remember The Brady Bunch?). In other words, only focus on the nine large squares (called “blocks”).
训练自己把整个棋盘看成3X3格，类似tic tac toe（三连棋游戏）。 用其他话说，就是只聚焦在这9个宫里。
With me so far? Ok now, we pick a number – I like to start with "1". Because of the rules of the game, the puzzle must have exactly nine 1s, and there will be one in each tic-tac-toe square (block).
然后从数字1开始。
你需要训练自己忽略其他数字。 如下图
然后你就可以解出1的位置：
Practice this enough, and it will become second nature to you.
通过足够的训练，这会变成你的第二天性
Of course, there is no guarantee you will find all the 1s. If there were, you could always solve every Sudoku using this technique.
当然，没有保证你可以找到所有的1.
Once you have found every “1” you can find, simply move on to “2”. Do the same thing for “3”, “4”, etc – all the way through “9”.
你找到所有可以填的1后，就开始填2,3,4，一直到9
Once you have finished with “9”, don't get too excited - you are not done. If you used “Visual Elimination” to fill in any cells, you will want to go right back to “1” and try again. This is because every filled cell potentially changes things. You have only truly exhausted this technique when you go from “1” all the way through “9” without solving any new cells.
9处理完成后，不要太高兴。 你应该会到1再继续尝试，因为中间你填了一些数，改变了状态。 只有你重复1~9一遍，一个数字都不能填进去，你才算完成。