/**
* Main pick function. If table size is greater then or equal to 16, it will use heuristic
* algorithm.
*
* @param limit maximum value of combinations
* @param items object value table
* @return solution
*/
public static <T> Pack<T> pick(Long limit, AbstractMap<T, Long> items) {
if (items.size() < 26) {
return Pack.binarySearch(limit, items);
} else {
return Pack.geneticAlgorithm(limit, items);
}
}
/**
* Back-end to pick using BFS.
*
* @param limit maximum value of combinations
* @param items object value table
* @return solution
*/
public static <T> Pack<T> breadthFirstSearch(Long limit, AbstractMap<T, Long> items) {
if (Pack.needSearch(limit, items)) {
return new Pack<T>(limit, new ArrayList<T>(items.keySet()));
}
ArrayList<Pack<T>> table = new ArrayList<Pack<T>>();
table.add(new Pack<T>());
for (Entry<T, Long> e : items.entrySet()) {
ArrayList<Pack<T>> tmp = new ArrayList<Pack<T>>();
for (Pack<T> p : table) {
Long newSize = p.getScore() + e.getValue();
if (newSize <= limit) {
ArrayList<T> newDirs = new ArrayList<T>(p.getItems());
newDirs.add(e.getKey());
tmp.add(new Pack<T>(newSize, newDirs));
}
}
table.addAll(table.size(), tmp);
}
Pack<T> max = new Pack<T>();
for (Pack<T> p : table) {
if (p.getScore() >= max.getScore()) {
max = p;
}
}
return max;
}
public Pack<T> call(int n, Pack<T> p) {
if (p.score_ > this.limit_) {
return new Pack<T>();
} else if (n == this.keys_.size()) {
return p;
} else {
Pack<T> a = this.call(n + 1, p);
Pack<T> b = this.call(n + 1, p.add(this.keys_.get(n), this.values_.get(n)));
if (a.compareTo(b) > 0) {
return a;
} else {
return b;
}
}
}
public Pack<T> call() {
while (!this.canStop()) {
this.crossOver();
this.mutation();
Collections.sort(this.population_);
this.population_.subList(this.table_.size(), this.population_.size()).clear();
}
Cell<T> survivor = this.population_.get(0);
Pack<T> result = new Pack<T>(survivor.getValue(), new ArrayList<T>());
for (Entry<T, Boolean> e : survivor.getTable().entrySet()) {
if (e.getValue()) {
result.getItems().add(e.getKey());
}
}
return result;
}
/**
* Back-end to pick using heuristic algorithm. The complexity is O(2^n).
*
* @param limit maximum value of combinations
* @param items object value table
* @return solution
*/
public static <T> Pack<T> geneticAlgorithm(Long limit, AbstractMap<T, Long> items) {
return (Pack.needSearch(limit, items))
? new GeneticAlgorithm<T>(limit, items).call()
: new Pack<T>(limit, new ArrayList<T>(items.keySet()));
}
/**
* Back-end to pick using DFS.
*
* @param limit maximum value of combinations
* @param items object value table
* @return solution
*/
public static <T> Pack<T> depthFirstSearch(Long limit, AbstractMap<T, Long> items) {
return (Pack.needSearch(limit, items))
? new DepthFirstSearch<T>(limit, items).call(0, new Pack<T>())
: new Pack<T>(limit, new ArrayList<T>(items.keySet()));
}
public static <T> Pack<T> binarySearch(Long limit, AbstractMap<T, Long> items) {
return (Pack.needSearch(limit, items))
? new BinarySearch<T>(limit, items).call()
: new Pack<T>(limit, new ArrayList<T>(items.keySet()));
}
