Submission #147254

#	Time	Username	Problem	Language	Result	Execution time	Memory
147254		ipaljak	Lun (COCI19_lun)	C++14	50 / 50	3 ms	376 KiB

lun

#include <bits/stdc++.h>

using namespace std;

#define TRACE(x) cerr << #x << " " << x << endl
#define FOR(i, a, b) for (int i = (a); i < int(b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define _ << " " <<

typedef long long llint;

const int MOD = 1e9 + 7;
const int MAXN = 105;

int n;
char s[MAXN];

bool check(int x) {
  int sum = 0;
  for (int i = 1; i < n; ++i) {
    int d = (s[n - i - 1] - '0');
    if (s[n - i - 1] == 'x') d = x;
    if (i % 2 == 1) d *= 2;
    if (d >= 10) d = 1 + (d % 10);
    sum += d;
  }
  sum *= 9; sum %= 10;
  int val = s[n - 1] - '0';
  if (s[n - 1] == 'x') val = x;
  return sum == val;
}

int main(void) {
  scanf("%d", &n);
  scanf("%s", s);

  for (int x = 0; x < 10; ++x) {
    if (s[0] == 'x' && x == 0) continue;
    if (check(x)) {
      printf("%d\n", x);
      break;
    }
  }

  return 0;
}

Compilation message (stderr)

lun.cpp: In function 'int main()':
lun.cpp:34:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &n);
   ~~~~~^~~~~~~~~~
lun.cpp:35:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%s", s);
   ~~~~~^~~~~~~~~

• Subtask 1: 50 / 50