UV problem 10042 Smith numbers (Smith number)

// Smith numbers (Smith number) // PC/Ultraviolet IDs: 110706/10042, popularity: B, success rate: average level: 1 // verdict: accepted // submission date: 2011-06-10 // UV Run Time: 0.060 S // copyright (c) 2011, Qiu. Metaphysis # Yeah dot net /// perform prime factor decomposition on the logarithm. Because the number is less than 10e9, if a certain number is a combination, then the prime factor must be at least one that is less than or equal to // SQRT (10e9), you can calculate 2-SQRT (10e9) first) the prime numbers between them are used as backups. # Include <iostream> # include <vector> # include <cmath> # include <ctime> using namespace STD; # define upbound 31623 // Ceil (SQRT (10e9 )) vector <int> prime; // stores prime numbers between 2-Ceil (SQRT (10e9) to facilitate problem solving. // Determine whether number N is a prime number. Bool is_prime (int n) {If (n = 2) return true; If (N % 2 = 0) return false; For (INT c = 3; c <= Ceil (SQRT (n); C + = 2) if (N % C = 0) return false; return true ;} // pregenerates a prime number between 2-Ceil (SQRT (10e9. Void find_prime () {Prime. push_back (2); For (INT c = 3; C <upbound; C ++ = 2) if (is_prime (c) Prime. push_back (c);} // calculates the sum of digits of number. Int digits_sum (INT number) {int sum = 0; while (number) {sum + = (Number % 10); Number/= 10;} return sum ;} void Smith (INT number) {int current = Number + 1; while (1) {// if it is a prime number, it is not a Smith number. If (is_prime (current) {current ++; Continue ;}// calculates the sum of digits of current. Int TMP = current; int sum = digits_sum (current), tsum = 0; // calculate the sum of the prime factors of the current number. While (1) {int memo = TMP; For (int c = 0; C <Prime. size (); C ++) if (TMP % prime [c] = 0) {tmp/= prime [c]; tsum + = digits_sum (prime [c]); break;} // If TMP is 1, all prime factors are found. If TMP is not changed, all prime factors are found at // 2-SQRT (10e9) between there is no TMP prime factor, TMP must be // is a prime number. If (TMP = 1 | memo = TMP) break;} // If TMP is not 1, it must be a prime number, because if it is a combination, no prime factor exists between 2-SQRT (10e9). This is impossible. In this case, all prime factors of this number are greater than SQRT (10e9 ), then // The number must be greater than 10e9, which is inconsistent with the question conditions. If (TMP> 1) tsum + = digits_sum (TMP); // you can specify whether the operators and digits are equal. If (tsum = sum) {cout <Current <Endl; break;} current ++ ;}} int main (int ac, char * AV []) {INT cases, number; find_prime (); CIN> cases; while (cases --) {CIN> Number; Smith (number) ;}return 0 ;}