Problem PARADOX from SPOJ

PARADOX.cpp

@@ -0,0 +1,58 @@
+// Problem : PARADOX from SPOJ
+
+#include <bits/stdc++.h>
+using namespace std;
+#define ll long long
+
+void dfs(int src, int next[], bool val[], int realVal[], bool& paradox, set<int>& nodes){
+	nodes.insert(src);
+	if(realVal[next[src]]!=-1){
+		// Paradox can occur only when the DAG has a cycle
+		if(nodes.find(next[src])!=nodes.end() && 
+			realVal[next[src]] == realVal[src] ^ val[src])paradox = true;
+	}
+	else{
+		realVal[next[src]] = !(realVal[src] ^ val[src]);
+		dfs(next[src], next, val, realVal, paradox, nodes);
+	}
+}
+
+void solve(int n){
+	int next[n],i;
+	bool val[n];
+	string s;
+	int realVal[n];
+	for(i=0;i<n;i++){
+		cin>>next[i]>>s;
+		val[i] = ((s=="true")?true:false);
+		next[i]--;
+		realVal[i] = -1;
+	}
+
+	bool paradox = false,compParadox = false;
+	set<int> nodes;
+
+	for(i=0;i<n;i++){
+		if(realVal[i] == -1){
+			realVal[i] = 1;
+			compParadox = false;
+			nodes.clear();
+			dfs(i,next,val,realVal,compParadox,nodes);
+			paradox = paradox || compParadox;		
+		}
+	}
+
+	cout<<((paradox)?"PARADOX":"NOT PARADOX");
+	return ;
+}
+
+int main(){
+	int t;
+	cin>>t;
+	while(t){
+		solve(t);
+		cin>>t;
+		if(t)cout<<"\n";
+	}
+	return 0;
+}