RandomizedStrategy.hpp

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#pragma once
 
#include "core/AlphaExpansion.hpp"
#include "strategies/ExpansionStrategy.hpp"
#include <vector>
#include <numeric>
#include <random>
#include <algorithm>
 
template <typename T>
class RandomizedStrategy : public ExpansionStrategy<T> {
public:
    RandomizedStrategy(int max_cycles = 100, unsigned int seed = 42)
        : max_cycles_(max_cycles), seed_(seed) {}
 
    int execute(AlphaExpansion<T> &optimizer, EnergyModel<T> &model) const override {
        int num_labels = model.num_labels();
        int cycle = 0;
        bool converged = false;
 
        std::vector<int> label_order(num_labels);
        std::iota(label_order.begin(), label_order.end(), 0);
        std::mt19937 g(seed_);
 
        while (!converged && cycle < max_cycles_) {
            bool any_changed = false;
            std::shuffle(label_order.begin(), label_order.end(), g);
            for (int alpha: label_order) {
                if (optimizer.perform_expansion_move(alpha)) any_changed = true;
            }
            if (!any_changed) converged = true;
            cycle++;
        }
        return cycle;
    }
 
private:
    int max_cycles_;
    unsigned int seed_;
};