[Add] solved solutions

cpp/GDOG.cpp

@@ -0,0 +1,19 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int t;
+    long long n, k, m;
+    cin >> t;
+    while (t--) {
+        cin >> n >> k;
+        m = 0;
+        for (long long i = 1; i <= k; ++i)
+            if (n % i > m)
+                m = n % i;
+        cout << m << endl;
+    }
+    return 0;
+}