/
cell.go
84 lines (74 loc) · 2.09 KB
/
cell.go
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/*
* Copyright © 2020, G.Ralph Kuntz, MD.
*
* Licensed under the Apache License, Version 2.0(the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIC
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package solver
import (
"strconv"
"strings"
)
type (
// Cell represents a single cell in the grid. Bits 1 through 9 are represented as a value where a bit
// is set if that digit is a candidate for the cell.
cell uint16
)
// String prints the string representation of a Cell.
func (c cell) String() string {
var s strings.Builder
for i := 1; i <= 9; i++ {
if c&(1<<i) != 0 {
s.WriteString(strconv.Itoa(int(i))) // nolint
}
}
return s.String()
}
// and ANDs the current cell with the other cell and returns true if the current cell changes.
func (c *cell) and(o cell) bool {
prev := *c
*c &= o
return *c != prev
}
// andNot ANDs the current cell with the complement of the other cell and returns true if the current cell changes.
func (c *cell) andNot(o cell) bool {
prev := *c
*c &= ^o
return *c != prev
}
func (c cell) digits() string {
var d []string
for i := 1; i <= 9; i++ {
if c&(1<<i) != 0 {
d = append(d, strconv.Itoa(int(i)))
}
}
return strings.Join(d, ", ")
}
// or ORs the current cell with the other cell and returns true if the current cell changes.
func (c *cell) or(o cell) bool {
prev := *c
*c |= o
return *c != prev
}
// replace replaces the current cell with the other cell and returns true if the current cell changes.
func (c *cell) replace(o cell) bool {
prev := *c
*c = o
return *c != prev
}
// xor XORs the current cell with the other cell and returns true if the current cell changes.
func (c *cell) xor(o cell) bool {
prev := *c
*c &^= o
return *c != prev
}