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prime_permutations.cpp
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prime_permutations.cpp
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#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
bool if_ap_exists(vector <int>& v) {
vector <int> ap;
int size = v.size();
int diff[size - 1][size];
for(int i = 0; i < size; i++) {
for(int j = i + 1; j < size; j++) {
diff[i][j] = v[j] - v[i];
}
}
for(int i = 0; i < size - 1 - 1; i++) {
for(int j = i + 1; j < size; j++) {
for(int m = i + 1; m < size - 1; m++) {
for(int n = m + 1; n < size; n++) {
if(diff[i][j] == diff[m][n]) {
if(j == m) {
ap.push_back(v[i]);
ap.push_back(v[j]);
ap.push_back(v[n]);
diff[m][n] = 0;
}
}
}
}
}
}
if(ap.size() != 0) {
for(auto x : ap) cout << x << " ";
return true;
}
return false;
}
bool is_permutation_of(int a, int b) {
vector <int> v1, v2;
while(a > 0) {
v1.push_back(a % 10);
a /= 10;
}
while(b > 0) {
v2.push_back(b % 10);
b /= 10;
}
if(v1.size() != v2.size()) return false;
sort(v1.begin(), v1.end());
sort(v2.begin(), v2.end());
for(int i = 0; i < v1.size(); i++) {
if(v1[i] != v2[i]) return false;
}
return true;
}
bool is_prime(int n) {
for(int i = 2; i * i <= n; i++) {
if(n % i == 0) return false;
}
return true;
}
int main(void) {
vector <int> v, u;
int flag;
for(int i = 1000; i < 10000; i++) {
if(is_prime(i)) v.push_back(i);
}
for(int i = 0; i < v.size(); i++) {
flag = 0;
for(int j = i + 1; j < v.size(); j++) {
if(is_permutation_of(v[i], v[j])) {
flag = 1;
u.push_back(v[j]);
v.erase(v.begin() + j);
j -= 1;
}
}
if(flag) {
u.insert(u.begin(), v[i]);
v.erase(v.begin() + i);
i -= 1;
if(u.size() > 2) {
if(if_ap_exists(u)) cout << endl;
}
u.clear();
}
}
return 0;
}