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  • Jongmah

    D. Jongmah
    time limit per test
    3 seconds
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    You are playing a game of Jongmah. You don't need to know the rules to solve this problem. You have nn tiles in your hand. Each tile has an integer between 11 and mm written on it.

    To win the game, you will need to form some number of triples. Each triple consists of three tiles, such that the numbers written on the tiles are either all the same or consecutive. For example, 7,7,77,7,7 is a valid triple, and so is 12,13,1412,13,14, but 2,2,32,2,3 or 2,4,62,4,6 are not. You can only use the tiles in your hand to form triples. Each tile can be used in at most one triple.

    To determine how close you are to the win, you want to know the maximum number of triples you can form from the tiles in your hand.

    Input

    The first line contains two integers integer nn and mm (1n,m1061≤n,m≤106) — the number of tiles in your hand and the number of tiles types.

    The second line contains integers a1,a2,,ana1,a2,…,an (1aim1≤ai≤m), where aiai denotes the number written on the ii-th tile.

    Output

    Print one integer: the maximum number of triples you can form.

    Examples
    input
    Copy
    10 6
    2 3 3 3 4 4 4 5 5 6
    output
    Copy
    3
    input
    Copy
    12 6
    1 5 3 3 3 4 3 5 3 2 3 3
    output
    Copy
    3
    input
    Copy
    13 5
    1 1 5 1 2 3 3 2 4 2 3 4 5
    output
    Copy
    4
    Note

    In the first example, we have tiles 2,3,3,3,4,4,4,5,5,62,3,3,3,4,4,4,5,5,6. We can form three triples in the following way: 2,3,42,3,4; 3,4,53,4,5; 4,5,64,5,6. Since there are only 1010 tiles, there is no way we could form 44 triples, so the answer is 33.

    In the second example, we have tiles 11, 22, 33 (77 times), 44, 55 (22 times). We can form 33 triples as follows: 1,2,31,2,3; 3,3,33,3,3; 3,4,53,4,5. One can show that forming 44 triples is not possible.

    #include <bits/stdc++.h>
    
    using namespace std;
    const int maxn=1e6+10;
    int dp[maxn][5][5],n,m,p[maxn];
    int main()
    {
        cin>>n>>m;
        for(int i=1;i<=n;i++){
            int tmp;
            scanf("%d",&tmp);
            p[tmp]++;
        }
        memset(dp,-127,sizeof(dp));
        dp[0][0][0]=0;
        for(int i=1;i<=m;i++){
            for(int j=0;j<3;j++){
                for(int k=0;k<3;k++){
                    for(int h=0;h<3;h++){
                         if(p[i]<h+j+k)continue;
                         dp[i][k][j]=max(dp[i][k][j],dp[i-1][h][k]+(p[i]-h-j-k)/3+h);
                    }
                }
            }
        }
        cout<<dp[m][0][0]<<endl;
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/czy-power/p/10582479.html
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