Codeforces/977/a.cpp

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#include <iostream>
namespace helpers {
using namespace std;
long pow(long base, long exp) {
if (exp == 0) return 1;
long half = pow(base, exp / 2);
if (exp % 2 == 0) return half * half;
return half * half * base;
}
template <typename T>
inline void answer(const T &ans) {
cout << ans << "\n";
}
} // namespace helpers
namespace {
using namespace std;
using namespace helpers;
int decrease(int n, int k) {
while (k > 0) {
if (n % 10 != 0) {
auto steps = min(n % 10, k);
n -= steps;
k -= steps;
} else {
n /= 10;
--k;
}
}
return n;
}
void solve() {
int n, k;
cin >> n >> k;
answer(decrease(n, k));
}
} // namespace
// for single test case, comment out for N test cases
#define SINGLE
#ifdef TEST
#include "../.common/cpp/catch_amalgamated.hpp"
TEST_CASE("examples") {
CHECK(decrease(512, 4) == 50);
CHECK(decrease(1000000000, 9) == 1);
}
#else
int main(void) {
#ifdef SINGLE
solve();
#else
// for multiple test cases
int N;
std::cin >> N >> std::ws;
for (auto i = 0; i < N; ++i) {
solve();
}
#endif
return 0;
}
#endif