Implement-Rand10()-Using-Rand7().cs

/**
 * The Rand7() API is already defined in the parent class SolBase.
 * public int Rand7();
 * @return a random integer in the range 1 to 7
 */
public class Solution : SolBase {
    public int Rand10() {
        while(true){
            int rand = 7*(Rand7() - 1) + (Rand7() - 1); // 0 to 48
            if(rand < 40) return rand % 10 + 1;
        }
    }
}