Submission #396721

#	Time	Username	Problem	Language	Result	Execution time	Memory
396721		rocks03	Paint By Numbers (IOI16_paint)	C++14	90 / 100	1494 ms	524292 KiB

paint

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define ff first
#define ss second
#define pb push_back
#define SZ(x) ((int)(x).size())
#define all(x) x.begin(), x.end()
#define debug(x) cout << #x << ": " << x << " "
#define nl cout << "\n"
#define rep(i, a, b) for(int i = (a); i < (b); i++)
#define per(i, a, b) for(int i = (a); i >= (b); i--)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int MAXK = 100+10;
const int MAXN = 2e5+100;
int N, K, a[MAXN], pr1[MAXN], pr2[MAXN], memo[MAXK][MAXN];
vector<int> c;

bool only_black(int l, int r){
    if(r >= N) return false;
    return (pr2[r + 1] - pr2[l] == (r - l + 1));
    /*
    rep(i, l, r + 1){
        if(a[i] == 0) return false;
    }
    return true;
    */
}

bool only_white(int l, int r){
    return ((pr1[r + 1] - pr1[l]) == 0);
    /*
    rep(i, l, r + 1){
        if(a[i] == 1) return false;
    }
    return true;
    */
}

bool col[2][MAXN];

multiset<int> st[MAXN], st2[MAXN];

void setrange(int l, int r, int k){
    if(l > r) return;
    r = min(r, N - 1);
    if(k != 0 && k != 1) return;
    /*
    rep(i, l, r + 1){
        col[k][i] = true;
    }
    */
    st[l].insert(k);
    st2[r + 1].insert(k);
}

void get(){
    multiset<int> s;
    rep(i, 0, N){
        for(int x : st[i]) s.insert(x);
        for(int x : st2[i]) s.erase(s.find(x));
        if(!SZ(s)) continue;
        if(*s.begin() == 0) col[0][i] = true;
        if(*s.rbegin() == 1) col[1][i] = true;
    }
}

int f(int i, int k){
    if(i >= N){
        if(k == K) return 1;
        return 0;
    }
    if(k == K){
        if(only_white(i, N - 1)){
            setrange(i, N - 1, 0);
            return 1;
        }
        return 0;
    }
    int& ans = memo[k][i];
    if(ans != -1){
        return ans;
    }
    ans = 0;
    if(a[i] == 0){
        ans = f(i + 1, k);
        if(ans == 1){
            setrange(i, i, 0);
        }
    } else if(a[i] == 1){
        int j = i + c[k];
        if(only_black(i, j - 1) && (j == N || a[j] != 1)){
            ans = f(j + 1, k + 1);
            if(ans == 1){
                setrange(i, j - 1, 1);
                setrange(j, j, 0);
            }
        }
    } else{
        ans = f(i + 1, k);
        if(ans == 1){
            setrange(i, i, 0);
        }
        int j = i + c[k];
        if(only_black(i, j - 1) && (j == N || a[j] != 1)){
            int ans2 = f(j + 1, k + 1);
            if(ans2 == 1){
                setrange(i, j - 1, 1);
                setrange(j, j, 0);
                ans = ans2;
            }
        }
    }
    return ans;
}

string solve_puzzle(string S, vector<int> C){
    N = SZ(S), K = SZ(C); c = C;
    rep(i, 0, N){
        if(S[i] == '_') a[i] = 0;
        else if(S[i] == 'X') a[i] = 1;
        else a[i] = -1;
    }
    rep(i, 0, N){
        pr1[i + 1] += pr1[i];
        pr2[i + 1] += pr2[i];
        if(a[i] >= 0) pr1[i + 1] += a[i], pr2[i + 1] += a[i];
        else pr1[i + 1] += 0, pr2[i + 1] += 1;
    }
    memset(memo, -1, sizeof(memo));
    memset(col, false, sizeof(col));
    f(0, 0);
    get();
    string answer = "";
    rep(i, 0, N){
        if(col[0][i] && col[1][i]){
            answer += '?';
        } else if(col[0][i]){
            answer += '_';
        } else if(col[1][i]){
            answer += 'X';
        } else assert(false);
    }
    return answer;
}

• 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: 0 / 10