Submission #1185927

#TimeUsernameProblemLanguageResultExecution timeMemory
1185927countlessPaint By Numbers (IOI16_paint)C++20
100 / 100
387 ms32608 KiB
/*
Notes:
- dp as more than just a recurrence but a transition between states and overlapping subproblems
- i'm maining pacman on super smash bros
- i suck at dp
- - but i'm going to get better i swear (trust)
- ever since i was a jit......................XXXXX______.......... <-- solve 1 2 3 4 5
*/

#include "paint.h"
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;

const ll MOD = 998244353;
const ll INF = 1e18;
const ld EPS = 1e-12;

#define endl "\n"
#define sp <<" "<<
#define REP(i, a, b) for(ll i = a; i < b; i++)
#define dbg(x) cout << #x << " = " << x << endl
#define mp make_pair
// #define pb push_back
#define fi first
#define se second
#define fast_io() ios_base::sync_with_stdio(false); cin.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((ll)(x).size())
#define try kwaz

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

template <typename Key, typename Value>
using hash_map = unordered_map<Key, Value, custom_hash>;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// uniform_int_distribution<int>(a, b)(rng);
// shuffle(all(a), rng);

// i shamelessly had to read the editorial; cries and dies.
string solve_puzzle(string s, vector<int> c) {
    int n = s.size(), k = c.size();
    string t(s.rbegin(), s.rend());
    vector<int> d(c.rbegin(), c.rend());

    vector<int> pw(n+1, 0), pb(n+1, 0);
    REP(i, 1, n+1) {
        pw[i] = pw[i-1] + (s[i-1] == '_');
        pb[i] = pb[i-1] + (s[i-1] == 'X');
    }

    auto try = [&](string ss, vector<int> &cc) -> vector<vector<bool>> {
        vector<int> ppww(n+1, 0), ppbb(n+1, 0);
        REP(i, 1, n+1) {
            ppww[i] = ppww[i-1] + (ss[i-1] == '_');
            ppbb[i] = ppbb[i-1] + (ss[i-1] == 'X');
        }

        vector<vector<bool>> res(n+1, vector<bool>(k+1, false));
        res[0][0] = true;

        REP(i, 1, n+1) {
            if (ss[i-1] != '_') {
                REP(j, 1, k+1) {
                    int l = i - cc[j-1];
                    int r = i;

                    if (j == 1) {
                        if (l >= 0 and ppbb[l] - ppbb[0] == 0 and ppww[r] - ppww[l] == 0)
                            res[i][j] = true;
                    }

                    else {
                        if (l >= 1 and ppww[r] - ppww[l] == 0 and ss[l-1] != 'X')
                            if (res[i - cc[j-1] - 1][j-1])
                                res[i][j] = true;
                    }
                }
            }

            if (ss[i-1] != 'X') {
                REP(j, 0, k+1) {
                    if (res[i-1][j])
                        res[i][j] = true;
                }
            }
        }

        return res;
    };

    vector<vector<bool>> dpf = try(s, c), dpb = try(t, d);
    reverse(all(dpb));

    vector<bool> cnw(n, false), cnb(n, false);
    REP(i, 0, n) {
        REP(j, 0, k+1) {
            if (s[i] != 'X' and dpf[i][j] and dpb[i+1][k-j])
                cnw[i] = true;
        }
    }

    REP(i, 0, k) {
        REP(j, 0, n - c[i] + 1) {
            bool flag = true;
            if (j > 0 and s[j-1] == 'X')
                flag = false;
            if (j + c[i] < n and s[j + c[i]] == 'X')
                flag = false;
            if (pw[j + c[i]] - pw[j] != 0)
                flag = false;
            if (!flag)
                continue;

            bool l = false, r = false;
            if (i == 0 and j == 0)
                l = true;
            else if (j >= 1 and s[j-1] != 'X' and dpf[j-1][i])
                l = true;

            if (i == k - 1 and j + c[i] - 1 == n - 1)
                r = true;
            else if (j + c[i] - 1 < n - 1 and s[j + c[i]] != 'X' and dpb[j + c[i] + 1][k - i - 1])
                r = true;

            if (l and r)
                REP(k, j, j + c[i])
                    cnb[k] = true;
        }
    }

    string ans(n, '~');
    REP(i, 0, n) {
        if (cnw[i] and cnb[i])
            ans[i] = '?';
        else if (cnw[i])
            ans[i] = '_';
        else if (cnb[i])
            ans[i] = 'X';
    }
    return ans;
}

// signed main() {
//     string s; cin >> s;
//     vector<int> c;
//     int x;
//     while (cin >> x)
//         c.push_back(x);

//     cout << solve_puzzle(s, c) << endl;
// }

Compilation message (stderr)

paint.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~
paint_c.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~
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