Submission #1031222

#	Time	Username	Problem	Language	Result	Execution time	Memory
1031222		c2zi6	Paint By Numbers (IOI16_paint)	C++14	100 / 100	688 ms	256552 KiB

paint

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define replr(i, a, b) for (int i = int(a); i <= int(b); ++i)
#define reprl(i, a, b) for (int i = int(a); i >= int(b); --i)
#define rep(i, n) for (int i = 0; i < int(n); ++i)
#define mkp(a, b) make_pair(a, b)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VPI;
typedef vector<VI> VVI;
typedef vector<VVI> VVVI;
typedef vector<VPI> VVPI;
typedef pair<ll, ll> PLL;
typedef vector<ll> VL;
typedef vector<PLL> VPL;
typedef vector<VL> VVL;
typedef vector<VVL> VVVL;
typedef vector<VPL> VVPL;
template<class T> T setmax(T& a, T b) {if (a < b) return a = b; return a;}
template<class T> T setmin(T& a, T b) {if (a < b) return a; return a = b;}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template<class T>
using indset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#include "paint.h"
 
struct PREFIXSUM {
    VI pref[3];
    PREFIXSUM(string s) {
        int n = s.size();
        pref[0] = pref[1] = pref[2] = VI(n+1);
        rep(i, n) {
            if (s[i] == '_') pref[0][i+1]++;
            else if (s[i] == 'X') pref[1][i+1]++;
            else if (s[i] == '.') pref[2][i+1]++;
            pref[0][i+1] += pref[0][i];
            pref[1][i+1] += pref[1][i];
            pref[2][i+1] += pref[2][i];
        }
    }
    int count(int l, int r, string s) {
        int ret = 0;
        for (char ch : s) if (ch == '_') ret += pref[0][r+1] - pref[0][l];
        else if (ch == 'X') ret += pref[1][r+1] - pref[1][l];
        else if (ch == '.') ret += pref[2][r+1] - pref[2][l];
        return ret;
    };
};

VVI solve(string s, VI c) {
    PREFIXSUM pref(s);
    int n = s.size();
    int k = c.size();
    VVI dp(n+1, VI(k+1));
    dp[0][0] = true;
    replr(i, 1, n) {
        if (s[i-1] == 'X') break;
        dp[i][0] = true;
    }
    replr(i, 1, n) replr(j, 1, k) {
        if (s[i-1] != 'X') dp[i][j] |= dp[i-1][j];
        int sz = c[j-1];
        if (i-sz < 0 || pref.count(i-sz, i-1, "_")) continue;
        if (i-sz == 0) dp[i][j] |= dp[0][j-1];
        else if (s[i-sz-1] != 'X') dp[i][j] |= dp[i-sz-1][j-1];
    }
    return dp;
}

string solve_puzzle(string s, VI c) {
    s = "_" + s + "_";
    int n = s.size();
    int k = c.size();
    VVI dpl = solve(s, c);
    reverse(all(s));
    reverse(all(c));
    VVI dpr = solve(s, c);
    reverse(all(s));
    reverse(all(c));
    PREFIXSUM pref(s);
    VI lus(n);
    VI rus(n);
    if (true) {
        int last;
        replr(i, 0, n-1) {
            if (s[i] == '_') last = i;
            lus[i] = last;
        }
        reprl(i, n-1, 0) {
            if (s[i] == '_') last = i;
            rus[i] = last;
        }
    }
    VVI payman(k, VI(n+1));
    rep(j, k) replr(i, 1, n-c[j]-1) {
        payman[j][i] = (
            s[i-1] != 'X' &&
            s[i+c[j]] != 'X' &&
            dpl[i-1][j] &&
            dpr[n-i-c[j]-1][k-j-1]);
        payman[j][i] += payman[j][i-1];
    }
    string ans(n, '?');
    replr(i, 1, n) {
        if (s[i] != '.') ans[i] = s[i];
        else {
            bool a = false;
            replr(j, 0, k-1) {
                int L = max({1, i-c[j]+1, lus[i]+1});
                int R = min({n-2, i+c[j]-1, rus[i]-1}) - c[j]+1;
                if (L <= R && payman[j][R] - payman[j][L-1]) a = true;
            }
            bool b = false;
            replr(j, 0, k) {
                if (dpl[i][j] && dpr[n-i-1][k-j]) {
                    b = true;
                }
            }
            if (a && !b) ans[i] = 'X';
            else if (!a && b) ans[i] = '_';
        }
    }
    ans = ans.substr(1, n-2);
    /*string real; cin >> real; if (real != ans) rep(i, 1000) cout << "ALERT ";*/
    return ans;
}
 
 

Compilation message (stderr)

paint.cpp: In function 'std::string solve_puzzle(std::string, VI)':
paint.cpp:94:20: warning: 'last' may be used uninitialized in this function [-Wmaybe-uninitialized]
   94 |             lus[i] = last;

• Subtask 1: 7 / 7
• Subtask 2: 3 / 3
• Subtask 3: 22 / 22
• Subtask 4: 27 / 27
• Subtask 5: 21 / 21
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10