{

unsigned int result{0};

const size_t size{vec.size()};

std::vector<std::pair<int, int>> p(size);

for(size_t i{0}; i<size; i++)

{

p[i].first = vec[i];

p[i].second = i;

}

// for descending order

std::sort(p.begin(), p.end(),

[](const std::pair<int,int> &p1, const std::pair<int,int> &p2){

return (p1.first > p2.first);

});

// keep visited nodes in deque

std::deque<bool> visited(size, false);

// find cycle in vector/array

// (edge number of the cycle - 1) is the minimum swap number

// if there is a back edge that means there is a cycle in the directed graph

for(size_t i{0}; i<size; i++)

{

if(visited[i] || p[i].second == static_cast<int>(i))

continue;

int edgeNumber{0};

size_t j {i};

while(!visited[j])

{

visited[j] = true;

j = p[j].second;

edgeNumber++;

}

if(edgeNumber > 0)

result += (edgeNumber - 1);

}

return result;

{

std::vector<int> vec{2, 4, 5, 1, 3};

std::cout<<numberOfSwap(vec)<<std::endl;

}