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import Color from '../../utils/Color';
/**
* Sorting Algorithm CountingSort
*
* Implementation based on pseudocode from Wikipedia.
*
* @author Bernhard Frick
* @param {number[]} elements
* @param {boolean} testing Set to true to test the algorithm
* @return {number[] || {do: {}[], undo: {}[]}[]}
*/
export default function CountingSort(elements, testing = false) {
const steps = [];
if (elements.length === 0) {
// nothing to sort
return testing ? Array.from(elements) : steps;
}
steps.push({
do: [{
action: Action.CLEAR,
}],
undo: [],
});
// get min and max from input for length of counts table
const min = Math.min(...elements);
const max = Math.max(...elements);
const inputTableSize = elements.length;
const countsTableSize = max - min + 1;
const outputTableSize = elements.length;
// create input, counts, output tables
steps.push({
do: [
{
action: Action.CREATE_TABLE,
id: 'inputTable',
title: 'Input',
rows: inputTableSize,
cols: 1,
},
{
action: Action.CREATE_TABLE,
id: 'countsTable',
title: 'Counts',
rows: countsTableSize,
cols: 2,
},
{
action: Action.CREATE_TABLE,
id: 'outputTable',
title: 'Output',
rows: outputTableSize,
cols: 1,
},
],
undo: [
{
action: Action.DELETE_TABLE,
id: 'inputTable',
},
{
action: Action.DELETE_TABLE,
id: 'countsTable',
},
{
action: Action.DELETE_TABLE,
id: 'outputTable',
},
],
});
// fill input table
let doActions = [];
let undoActions = [];
for (let i = 0; i < inputTableSize; i += 1) {
doActions.push({
action: Action.SET_CELL_VALUE,
id: 'inputTable',
row: i,
col: 0,
value: elements[i],
});
undoActions.push({
action: Action.SET_CELL_VALUE,
id: 'inputTable',
row: i,
col: 0,
value: null,
});
}
steps.push({
do: doActions,
undo: undoActions,
});
// fill countsTable values (first col)
doActions = [];
undoActions = [];
for (let i = 0; i < countsTableSize; i += 1) {
doActions.push({
action: Action.SET_CELL_VALUE,
id: 'countsTable',
row: i,
col: 0,
value: min + i,
});
undoActions.push({
action: Action.SET_CELL_VALUE,
id: 'countsTable',
row: i,
col: 0,
value: null,
});
}
steps.push({
do: doActions,
undo: undoActions,
});
const counts = new Map();
// fill countsTable counts (second col)
for (let i = 0; i < inputTableSize; i += 1) {
// highlight input
steps.push({
do: [{
action: Action.SET_ROW_COLOR,
id: 'inputTable',
row: i,
color: Color.TH_CURRENT_ELEMENT,
text: '',
}],
undo: [{
action: Action.SET_ROW_COLOR,
id: 'inputTable',
row: i,
color: Color.BASE_COLOR_TABLE_HORIZONTAL,
text: '',
}],
});
// highlight count
steps.push({
do: [{
action: Action.SET_ROW_COLOR,
id: 'countsTable',
row: elements[i] - min,
color: Color.TH_CURRENT_ELEMENT,
text: '',
}],
undo: [{
action: Action.SET_ROW_COLOR,
id: 'countsTable',
row: elements[i] - min,
color: Color.BASE_COLOR_TABLE_HORIZONTAL,
text: '',
}],
});
// increase count
if (counts.has(elements[i])) {
counts.set(elements[i], counts.get(elements[i]) + 1);
steps.push({
do: [{
action: Action.SET_CELL_VALUE,
id: 'countsTable',
row: elements[i] - min,
col: 1,
value: counts.get(elements[i]),
}],
undo: [{
action: Action.SET_CELL_VALUE,
id: 'countsTable',
row: elements[i] - min,
col: 1,
value: counts.get(elements[i]) - 1,
}],
});
} else {
counts.set(elements[i], 1);
steps.push({
do: [{
action: Action.SET_CELL_VALUE,
id: 'countsTable',
row: elements[i] - min,
col: 1,
value: 1,
}],
undo: [{
action: Action.SET_CELL_VALUE,
id: 'countsTable',
row: elements[i],
col: 1,
value: null,
}],
});
}
// clear both highlights
steps.push({
do: [
{
action: Action.SET_ROW_COLOR,
id: 'inputTable',
row: i,
color: Color.BASE_COLOR_TABLE_HORIZONTAL,
text: '',
},
{
action: Action.SET_ROW_COLOR,
id: 'countsTable',
row: elements[i] - min,
color: Color.BASE_COLOR_TABLE_HORIZONTAL,
text: '',
},
],
undo: [
{
action: Action.SET_ROW_COLOR,
id: 'inputTable',
row: i,
color: Color.TH_CURRENT_ELEMENT,
text: '',
},
{
action: Action.SET_ROW_COLOR,
id: 'countsTable',
row: elements[i] - min,
color: Color.TH_CURRENT_ELEMENT,
text: '',
},
],
});
}
// sort the counts (view is already sorted)
const countsSorted = new Map([...counts.entries()].sort(([va], [vb]) => Math.sign(va - vb)));
// loop over counts to fill outputTable
const sorted = [];
let sortedPointer = 0;
countsSorted.forEach((count, value) => {
// highlight count for 'value' in countsTable
steps.push({
do: [{
action: Action.SET_ROW_COLOR,
id: 'countsTable',
row: value - min,
color: Color.TH_CURRENT_ELEMENT,
}],
undo: [{
action: Action.SET_ROW_COLOR,
id: 'countsTable',
row: value - min,
color: Color.BASE_COLOR_TABLE_HORIZONTAL,
}],
});
// insert values into output
for (let i = 0; i < count; i += 1) {
sorted.push(value);
steps.push({
do: [{
action: Action.SET_CELL_VALUE,
id: 'outputTable',
row: sortedPointer,
col: 0,
value,
}],
undo: [{
action: Action.SET_CELL_VALUE,
id: 'outputTable',
row: sortedPointer,
col: 0,
value: null,
}],
});
steps.push({
do: [{
action: Action.SET_ROW_COLOR,
id: 'outputTable',
row: sortedPointer,
col: 0,
color: Color.TH_ELEMENT_SORTED,
}],
undo: [{
action: Action.SET_ROW_COLOR,
id: 'outputTable',
row: sortedPointer,
col: 0,
color: Color.BASE_COLOR_TABLE_HORIZONTAL,
}],
});
sortedPointer += 1;
}
// clear highlight count for 'value' in countsTable
steps.push({
do: [{
action: Action.SET_ROW_COLOR,
id: 'countsTable',
row: value - min,
color: Color.BASE_COLOR_TABLE_HORIZONTAL,
}],
undo: [{
action: Action.SET_ROW_COLOR,
id: 'countsTable',
row: value - min,
color: Color.TH_CURRENT_ELEMENT,
}],
});
});
return testing ? sorted : steps;
}
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