Created
December 12, 2015 17:43
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Jumping frog
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// The frog start at position -1, the river starts at position 0, the frog must go to position river size (path) or bigger | |
// Compile with c++11, e.g. in clang++: clang++ frog.cpp -std=c++11 | |
#include <vector> | |
#include <iostream> | |
#include <tuple> | |
typedef std::vector<int> Path; | |
typedef std::vector<std::tuple<int, int> > Visited; | |
bool walk(const int pos, const int speed, const Path& path, Visited& visited, Visited& walking); | |
static int ts = 0; | |
int main() { | |
Path path = {0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0, 0, 1, 0, 1}; | |
Visited visited; | |
int pos = -1; | |
int speed = 0; | |
Visited walking; | |
if (walk(pos, speed , path, visited, walking)) { | |
std::cerr << "#ops: " << ts << std::endl; | |
std::cerr << "***** " << walking.size() << " ***** " << std::endl; | |
for (auto w: walking) { | |
std::cerr << std::get<0>(w) << " " << std::get<1>(w) << std::endl; | |
} | |
return 0; | |
} | |
return 1; | |
} | |
bool walk(const int pos, const int speed, const Path& path, Visited& visited, Visited& walking) { | |
ts++; | |
if (std::find(visited.begin(), visited.end(), std::make_tuple(pos, speed)) != visited.end()) { | |
return false; | |
} | |
visited.emplace_back(pos, speed); | |
// Crossed the river | |
if (pos >= (signed) (path.size())) { | |
walking.push_back(std::make_tuple(pos, speed)); | |
return true; | |
} | |
// Is on some block? | |
if (pos >= 0 && !path[pos]) { | |
return false; | |
} | |
// Too far from the river | |
if (pos <= (-10 * (signed) path.size())) { | |
return false; | |
} | |
std::vector<Visited> walkings; | |
Visited walking1; | |
if (walk(pos + (speed + 1), speed + 1, path, visited, walking1)) { | |
walkings.push_back(walking1); | |
} | |
Visited walking2; | |
if (walk(pos + speed, speed, path, visited, walking2)) { | |
walkings.push_back(walking2); | |
} | |
Visited walking3; | |
if (walk(pos + (speed - 1), speed - 1, path, visited, walking3)) { | |
walkings.push_back(walking3); | |
} | |
if (walkings.empty()) { | |
return false; | |
} | |
std::sort(walkings.begin(), walkings.end(), [](Visited& a, Visited& b) { | |
return a.size() < b.size(); | |
}); | |
walking = walkings[0]; | |
walking.push_back(std::make_tuple(pos, speed)); | |
return true; | |
} |
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