Submission #612469

#	Time	Username	Problem	Language	Result	Execution time	Memory
612469		drdilyor	Match (CEOI16_match)	C++17	10 / 100	1 ms	340 KiB

match

#include <bits/stdc++.h>
#ifdef ONPC
    #include "t_debug.cpp"
#else
    #define debug(...) 42
#endif
#define sz(a) ((int)(a).size())
using namespace std;
using ll = long long;
const int INF = 1e9;
const ll INFL = 1e18;
const int RANDOM = chrono::high_resolution_clock::now().time_since_epoch().count();
mt19937 rng(RANDOM);
template<typename T, typename U> istream& operator>>(istream& is, pair<T, U>& p) { return is >> p.first >> p.second; }
const int N = 2e5, LOGN = 17, MOD = 1e9+7;

string solve(const string& s) {
    int n = s.size();
    string res(n, '?');
    vector<array<int, 26>> count(n);
    for (int i = 0; i < n; i++) {
        if (i) count[i] = count[i-1];
        count[i][s[i]-'a']++;
    }

    auto valid = [&](int i, int j) {
        for (int k = 0; k < count[i].size(); k++) {
            if ((count[j][k] - count[i-1][k]) % 2)
                return false;
        }
        int depth = 0;
        for (; i <= j; i++) {
            if (res[i] =='(') depth++;
            if (res[i] == ')') depth--;
            if (depth < 0) return false;
        }
        return depth == 0;
    };

    for (int i = 0; i < n; i++) {
        if (res[i] != '?') continue;
        int depth = 0;
        for (int j = n-1; j > i; j--) {
            if (s[i] != s[j]) continue;
            if (res[j] != '?') continue;

            if (valid(i+1, j-1)) {
                res[i] = '(';
                res[j] = ')';
                break;
            }
        }
        if (res[i] == '?') {
            return "-1";
        }
    }
    return res;
}

string solve_2(const string& s) {
    int n = s.size();
    string res(n, '?');
    function<bool(int)> brute = [&](int i) {
        if (i < n) {
            res[i] = '(';
            if (brute(i+1)) return true;
            res[i] = ')';
            return brute(i+1);
        } else {
            vector<int> matching(n, -1);
            vector<int> cur;
            for (int i = 0; i < n; i++) {
                if (res[i] == '(') {
                    cur.push_back(i);
                } else {
                    if (cur.empty()) return false;
                    matching[i] = cur.back();
                    matching[cur.back()] = i;
                    cur.pop_back();
                }
            }
            if (!cur.empty()) return false;
            for (int i = 0; i < n; i++) {
                if (s[i] != s[matching[i]]) return false;
                int depth = 0;
                for (int j = i+1; j < matching[i]; j++) {
                    if (res[j] == '(') depth++;
                    else depth--;
                    if (depth < 0) return false;
                }
                if (depth != 0) return false;
            }
            return true;
        }
    };
    return brute(0) ? res : "-1";
}

signed main() {
    int t = 1;
    #ifdef ONPC
    cin >> t;
    #endif
    while (t-- && cin) {
        string s; cin >> s;
        if (!cin) break;
        #ifdef ONPC
        cout << "Case " << s << '\n';
        string res1 = solve(s), res2 = solve_2(s);
        cout << res1 << endl;
        if (res1 != res2) {
            cout << res2 << endl;
            cout << "Case " << s << '\n';
            assert(false);
        }
        #else
        cout << solve(s);
#endif
    }
    return 0;
}

/*
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▒███ ▒███  ▒███ ▒▒▒ ▒███ ▒███  ▒███  ▒███  ▒███ ▒███ ▒███ ▒███ ▒███ ▒▒▒ 
▒███ ▒███  ▒███     ▒███ ▒███  ▒███  ▒███  ▒███ ▒███ ▒███ ▒███ ▒███     
▒▒████████ █████    ▒▒████████ █████ █████ ▒▒███████ ▒▒██████  █████    
 ▒▒▒▒▒▒▒▒ ▒▒▒▒▒      ▒▒▒▒▒▒▒▒ ▒▒▒▒▒ ▒▒▒▒▒   ▒▒▒▒▒███  ▒▒▒▒▒▒  ▒▒▒▒▒     
                                            ███ ▒███                    
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*/

Compilation message (stderr)

match.cpp: In lambda function:
match.cpp:27:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::array<int, 26>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |         for (int k = 0; k < count[i].size(); k++) {
      |                         ~~^~~~~~~~~~~~~~~~~
match.cpp: In function 'std::string solve(const string&)':
match.cpp:42:13: warning: unused variable 'depth' [-Wunused-variable]
   42 |         int depth = 0;
      |             ^~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 27
• Subtask 3: 0 / 63