text 统计一个区间内某个数字的出现次数

Posted 2021-04-29

#include <random>
#include <iostream>

using namespace std;

int main() {
    int a, b;
    cin >> a >> b;
    string s = "";
    for (int i = a; i <= b; ++i) {
        s.append(to_string(i));
    }
    int ant = 0;
    for (int j = 0; j < s.length(); ++j) {
        if (s[j] == '2') {
            ant++;
        }
    }
    cout << ant;
}