Submission #1606424

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)
#define unless(p) if(!(p))
#define until(p) while(!(p))

using ll = long long;
using P = std::tuple<int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

int as[5100];
bool dp[5100][5100], dp2[5100][5100];

int main(){
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    int N, K;
    std::cin >> N >> K;

    for(int i=1;i<=N;++i){
        std::cin >> as[i];
    }

    dp[0][0] = 1;
    for(int i=1;i<=N;++i){
        for(int j=0;j<K;++j){
            dp[i][j] |= dp[i-1][j];
            if(j - as[i] >= 0){
                dp[i][j] |= dp[i-1][j-as[i]];
            }
        }
    }

    dp2[N+1][0] = 1;
    for(int i=N;i>=1;--i){
        for(int j=0;j<K;++j){
            dp2[i][j] |= dp2[i+1][j];
            if(j - as[i] >= 0){
                dp2[i][j] |= dp2[i+1][j-as[i]];
            }
        }
    }    
    
    int res = 0;
    for(int i=1;i<=N;++i){        
        queue<int> q;
        int k = K - 1;
        bool isNeeded = false;
        for(int j=0;j<K;++j){
            // [lb, ub)
            int lb = max(0, K - as[i] - j),
                ub = K - j;
            
            while(lb <= k && k < ub){
                if(dp2[i+1][k]){
                    q.emplace(k);
                }
                --k;
            }

            if(not q.empty() && (q.front() < lb || ub <= q.front())){
                q.pop();
            }

            if(dp[i-1][j] && not q.empty()){
                isNeeded = true;
            }
        }

        if(not isNeeded){
            // std::cout << "! " << i << std::endl;
            ++res;
        }
    }

    std::cout << res << std::endl;
}

Submission Info

Judge Result