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399. Evaluate Division.cpp
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399. Evaluate Division.cpp
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class Solution {
public:
void DFS(string start,string end,map<string,double>& mp,map<string,vector<string>>& graph,double& val,map<string,int>& visited,bool& found){
visited[start]=1;
if(found==true)
return ;
for(auto child:graph[start]){
if(visited[child]!=1){
val*=mp[start+"->"+child];
if(end==child){
found=true;
return ;
}
DFS(child,end,mp,graph,val,visited,found);
if(found==true){
return ;
}
else{
val/=mp[start+"->"+child];
}
}
}
}
vector<double> calcEquation(vector<vector<string>>& equations, vector<double>& values, vector<vector<string>>& queries) {
vector<double> ans;
map<string,double> mp;
map<string,vector<string>> graph;
for(int i=0;i<equations.size();i++){
string u=equations[i][0];
string v=equations[i][1];
mp[u+"->"+v]=values[i];
mp[v+"->"+u]=1/values[i];
graph[u].push_back(v);
graph[v].push_back(u);
}
for(int i=0;i<queries.size();++i){
string start = queries[i][0];
string end = queries[i][1];
if(graph.find(start) == graph.end()||graph.find(end) == graph.end()){
ans.push_back(-1);
}else{
double val = 1;
map<string,int> visited;
bool found = false;
if(start == end){
found=true;
}
else DFS(start,end,mp,graph,val,visited,found);
if(found==true) ans.push_back(val);
else ans.push_back(-1);
}
}
return ans;
}
};