Values in unordered_map are changing itself - c++

Question

Having trouble with unordered_map named visited.
The goal of visited is to mark visited vertices in graph which are pairs of char and int.
The problem is that values in visited change itself even if I changed them manually after the initialization of visited.
I tried simpler method to declare hash for pair of int and char but it didn't work.
Then I tried to change pair of char and int to int, by multiplicating char by 1M and adding int.
However it didn't work either.
Details:
When function BFS is called again then the same key (i.e. key is pair<'c', 1> converted to int)
is called in condition:
if ( visited[(pair.first - '0')*1000000 + pair.second] == 0 )
then the condition is passed even if I assign to this key a value of 1 earlier.
#include <vector>
#include <unordered_map>
#include <list>
#include <utility>
using namespace std;
typedef std::pair<char, int> p;
// define hash for pair<char, int>
struct pair_hash
{
template <class T1, class T2>
std::size_t operator() (const std::pair<T1, T2> &p) const
{
return std::hash<T1>()(p.first) ^ std::hash<T2>()(p.second);
}
};
void BFS(pair<char, int> v,
unordered_map<int, int> visited,
unordered_map<pair<char, int>, vector<pair<char, int>>, pair_hash> graph) {
// Maybe int instead of a pair<char, int> as a key will work...
int x = (v.first - '0')*1000000 + v.second;
if (visited[x] == 0) {
// Create a queue for BFS
list<pair<char, int>> queue;
// Mark the current node as visited and enqueue it
visited[x] = 1;
queue.push_back(v);
while(!queue.empty()) {
// Dequeue a vertex from queue
v = queue.front();
queue.pop_front();
// Get all adjacent vertices of the dequeued
// vertex s. If a adjacent has not been visited,
// then mark it visited and enqueue it
for (p P : graph[v]) {
int y = (P.first - '0')*1000000 + P.second;
// Problem lays here
if (visited[y] == 0) {
// now I set converted pair<'c', 1> to int to 1:
visited[y] = 1;
// After 1, 2 calls of function named BFS the condtion
// if ( visited[ converted pair<'c', 1> to int ] == 0 )
// is passed even if I set it to 1 earlier
queue.push_back(P);
}
}
}
}
}
int main() {
unordered_map<pair<char, int>, vector<pair<char, int>>, pair_hash> graph;
// Container for marking vertices as visited
unordered_map<int, int> visited;
for (auto kv: graph) {
int x = (kv.first.first - '0')*1000000 + kv.first.second;
visited[x] = 0;
}
// Graph traversal
for (auto kv: graph) {
BFS(kv.first, visited, graph);
}
}
return 0;
}