Altered Algorithm

Algorithm/BackTracking/UVa524-PrimeRingProblem.cpp

@@ -0,0 +1,59 @@
+#include <iostream>
+#include <vector>
+using namespace std;
+vector<vector<int>> result;
+bool prime(int x){
+    if(x <= 1) return false;
+    for(int i = 2; i * i <= x; i++){
+        if(x % i == 0) return false;
+    }
+    return true;
+}
+
+
+bool checkPrime(int n, vector<int>& x) {
+    if (x.size() < 2) return true; // <20><><EFBFBD><EFBFBD>2<EFBFBD><32><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ü<EFBFBD><C3BC><EFBFBD>
+
+    int tmp = x[x.size() - 1] + x[x.size() - 2];
+    if (!prime(tmp)) return false;
+
+    if (x.size() == n) {
+        if (!prime(x.back() + x[0])) return false;
+    }
+    return true;
+}
+
+
+void dfs(int n, vector<int>& _path, vector<bool>& _used){
+	if(!checkPrime(n, _path)) return;
+	if(_path.size() == n){
+		result.push_back(_path);
+		return;
+	} 
+	for(int i = 0; i < n; i++){
+		if(!_used[i]){
+			_used[i] = true;
+			_path.push_back(i + 1);
+			dfs(n, _path, _used);
+			_used[i] = false;
+			_path.pop_back();
+		}
+		
+	}
+}
+int main(){
+	int n;
+	cin >> n;
+	vector<bool> used(n, false);
+	vector<int> path;
+	dfs(n, path, used);
+	for(auto x : result){
+		for(auto y : x){
+			cout << y << " ";
+		}
+		cout << endl;
+	}
+	cout << endl;
+	system("pause");
+	return 0;
+}