Sudoku Cities

For each Sudoku that you solve, we show you incredible pictures of the most beautiful cities in the world...

This game has 4 Sudoku levels: Easy, Medium, Hard and Professional,and images of the 50 most beautiful cities in the World...

The numbers in the game sudoku are generated randomly. Arithmetic relations between numbers, are absolutely necessary irrelevantes.Não is no mathematical logic or calculation capacity. They can use any combination of different symbols (such as letters, shapes, or colors) without changing the rules.

The success of the game due to the fact that the rules are so simple, however, the line of reasoning required to reach the solution can be complex. Sudoku is recommended by some teachers as an exercise in logical thinking. The level of difficulty can be selected to match the audience. There are several sources on the Internet are not linked to publishers that provide the games for free.

Their size is most often a 9x9 grid made up of sub-3x3 grids called "regions" (other terms include "boxes" and "blocks", sometimes, the term "quadrant" is used, although a term inaccurate for a grid of 3x3). Some cells already containing numbers, called "number data" (or sometimes "tracks"). The goal is to fill the empty cells with a number in each cell, so that each column, row and region contains the numbers 1 to 9 only once. In the solution of the game, each number appears only once in either direction or regions; hence, the term sudoku, which means "single number".

The 3x3 region in the upper right corner. The solver can eliminate all the empty cells in the upper right corner containing one 5 in the same columns or rows.

Scanning is performed at the beginning and throughout the solution. Scans only have to be performed once between periods of analysis. Scanning consists of two basic techniques:

Crossing: the scanning of rows (or columns) to identify which line in a particular region may contain a certain number by a process of elimination. This process is then repeated with the columns (or rows). For faster results, the numbers are checked in order of frequency. It is important to perform this process systematically, checking all of the digits 1-9.

Count the numbers 1-9 in regions, rows and columns to identify missing numbers. Counting number based on the latest discovered may cause the search is faster. It may also be the case (typically in tougher puzzles) that the easiest way to check the value of an individual cell is counting in reverse - that is, scanning of the cell region, row, and column for values that "can not" be, in order to discover what remains.

Advanced solvers look for "contingencies" while scanning - that is, strengthening the position of a numeral in a row, column, or region to two or three cells. When those cells all lie within the same row (or column) "and" region, they can be used for elimination purposes during cross steps and counting. [4] In particular, the more challenging puzzles may require multiple contingencies to be discovered perhaps in multiple directions or even multiple intersections. The puzzles that can be solved by making the scan without detection of contingencies are classified as "easy" puzzles; more difficult puzzles, by definition, can not be solved by basic scanning alone.