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@jremmen
Created June 20, 2013 06:34
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js:knapsack object, returns optimal solution in total value, total weight, items selected, and a binary selection process
var Knapsack = function(o) {
this.values = o.values;
this.weights = o.weights;
this.capacity = o.capacity;
this.createSolutionTable = function () {
this.table = this.initializeMatrix();
for(i = 1; i <= this.values.length; i++) {
for(k = 0; k < this.capacity; k++) {
if(k - this.weights[i - 1] >= 0) {
this.table[i][k] = Math.max(this.table[i - 1][k], this.values[i - 1] + this.table[i - 1][k - this.weights[i - 1]]);
} else {
this.table[i][k] = this.table[i - 1][k];
}
}
}
return this.table;
};
this.getOptimalSolution = function() {
var result = [];
for(i = this.table.length - 1, k = this.table[0].length - 1; k >= 0 && i > 0; i--) {
if(this.table[i][k] !== this.table[i - 1][k]) {
result.push({
index: i,
value: this.values[i - 1],
weight: this.weights[i - 1]
});
k -= this.weights[i - 1];
}
}
return result.reverse();
};
this.getOptimalSolutionBinary = function() {
var result = [];
for(i = this.table.length - 1, k = this.table[0].length - 1; k >= 0 && i > 0; i--) {
if(this.table[i][k] !== this.table[i - 1][k]) {
result.push(1);
k -= this.weights[i - 1];
} else {
result.push(0);
}
}
return result.reverse().toString().replace(/,/g, ' ');
}
this.initializeMatrix = function() {
var matrix = [];
for(i = 0; i < this.values.length + 1; i++) {
matrix[i] = [];
for(k = 0; k < this.capacity; k++) {
matrix[i][k] = 0;
}
}
return matrix;
};
this.getOptimalTotalWeight = function() {
return this.getOptimalSolution().reduce(function(x, y) { return { weight: x.weight + y.weight } });
}
this.getOptimalTotalValue = function() {
return this.getOptimalSolution().reduce(function(x, y) { return { value: x.value + y.value } });
}
this.table = this.createSolutionTable();
}
var options = {
values: [8, 10, 15, 4, 12, 3],
weights: [4, 5, 8, 3, 6, 5],
capacity: 19
};
sack = new Knapsack(options);
results = {
totalValue: sack.getOptimalTotalValue(),
totalWeight: sack.getOptimalTotalWeight(),
selectedItems: sack.getOptimalSolution(),
binaryResult: sack.getOptimalSolutionBinary()
}
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