12542 solved

12542.cpp

@@ -0,0 +1,62 @@
+#include <iostream>
+#include <string>
+#include <cmath>
+#include <vector>
+#include <sstream>
+using namespace std;
+
+#define pow2(i) (1<<i)
+#define bit(i) (1<<i)
+#define isOdd(i) (i&1)
+#define isEven(i) (!(i&1))
+#define sz(i) i.size()
+#define REP(i, b, n) for (int i = b; i < n; i++)
+#define REPI(i, b, n) for (int i = b; i <= n; i++)
+#define rep(i, n) REP(i, 0, n)
+#define repi(i, n) REPI(i, 0, n)
+
+bool is_prime(int n) {
+    if (n == 2) return true;
+    if (n < 3) return false;
+    if (n % 2 == 0) return false;
+
+    for (int i = 3, sq = sqrt(n); i <= sq; i += 2) {
+        if (n % i == 0)
+            return false;
+    }
+
+    return true;
+}
+
+string int_to_string(int n) {
+    stringstream ss;
+    ss << n;
+    return ss.str();
+}
+
+int main(void) {
+    string input;
+    vector<string> primes;
+
+    primes.push_back("2");
+
+    for (int i = 3; i < 100000; i += 2) {
+        if (is_prime(i)) {
+            primes.push_back(int_to_string(i));
+        }
+    }
+
+    while (getline(cin, input)) {
+        if (input == "0")
+            break;
+
+        for (vector<string>::reverse_iterator it = primes.rbegin(); it != primes.rend(); it++) {
+            if (input.find(*it) != string::npos) {
+                cout << *it << endl;
+                break;
+            }
+        }
+    }
+
+    return 0;
+}