Chapter 13, Problem 22PE

Program Plan Intro

8 Queens Problem

Program plan:

Filename: “PartialSolution.java”

This code snippet creates an interface “PartialSolution”. In the code,

• Define a class “PartialSolution”.
  • Declare the interface variables.
  • Declare the method “examine()”.
  • Declare the variables “extend()”.

Filename: “EightQueensPartialSolution.java”

This code snippet creates a class “EightQueensPartialSolution”. In the code,

• Define a class “EightQueensPartialSolution”.
  • Declare the class variables.
  • Define the constructor “EightQueensPartialSolution”.
    • Define the array “queens”.
  • Define the method “examine()”.
    • Iterate a “for” loop,
      • Iterate the inner “for” loop,
        • If “queens[i]” attacks “queens[j]”.
        • • Return the value of “ABANDON”.
            • If the length of the “queens” is “NQUEENS”,
              • Return the value of “ACCEPT”.
            • Else,
              • Return the value of “CONTINUE”.
  • Define the method “extend()”.
    • Set the value of “result”.
    • Iterate a “for” loop,
      • Get the length of “queens” to “size”.
      • Set the “result[i]”.
      • Iterate a “for” loop,
        • Set “queen[j]” to “result[i]”.
        • • • • • Append the new queen to “ith” column.
            • Return the value of “result”.
  • Define a method “toString()”.
    • Return the queens.

Filename: “Queen.java”

This code snippet creates a class “Queen”. In the code,

• Define a class “Queen”.
  • Define the class members “row” and “column”.
  • Define a constructor “Queen()”.
    • Set the value of “row” and “column”.
  • Define the method “attacks()”.
    • Return the result of logical operation.
  • Define a method “toString()”.
    • Return the value.

Filename: “Solver.java”

This code snippet creates a class “Solver”. In the code,

• Define a class “Solver”.
  • Define the method “Solve()”.
  • Define an integer “exam”.
  • If the value of “exam” is equal to “ACCEPT”,
    • Print the value of “sol”.
  • Else if the value of “exam” is equal to “ABANDON”,
    • Iterate a “for” loop,
      • Call the method “solve()”.

Filename: “EightQueens.java”

This code snippet creates a class “EightQueens”. In the code,

• Define a class “EightQueens”.
  • Define the “main” method.
    • Call the method “solve()”.