Decimal Sequences

p7412.cpp

// Asia-Tsukuba 2015 Regionals

#include <iostream>
#include <cstring>
#include <cmath>

using namespace std;

int main() {
    int n, temp, i, smallest, tempj;
    int board[1000];
    bool present[10000];
    bool solved;

    while (cin >> n) {
        solved = false;
        memset(present, false, sizeof present);
        for (i = 0; i < n; i++) {
            cin >> temp;
            board[i] = temp;
        }
        // i here is num digits of the smallest integer
        for (i = 0; i < n; i++) {
            if (solved) break;
            for (int j = 0; j < n - i; j++) {
                temp = 0;
                tempj = j;
                for (int k = i; k >= 0; k--) {
                    temp += board[tempj++] * pow(10, k);
                }
                present[temp] = true;
            }
            for (int j = pow(10, i) - 1; j < pow(10, i + 1); j++) {
                if (!present[j]) {
                    solved = true;
                    smallest = j;
                    break;
                }
            }
        }
        cout << smallest << endl;
    }

    return 0;
}