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  • Codeforces 611C. New Year and Domino 动态规划

    C. New Year and Domino
    time limit per test
    3 seconds
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    They say "years are like dominoes, tumbling one after the other". But would a year fit into a grid? I don't think so.

    Limak is a little polar bear who loves to play. He has recently got a rectangular grid with h rows and w columns. Each cell is a square, either empty (denoted by '.') or forbidden (denoted by '#'). Rows are numbered 1 through h from top to bottom. Columns are numbered 1 through w from left to right.

    Also, Limak has a single domino. He wants to put it somewhere in a grid. A domino will occupy exactly two adjacent cells, located either in one row or in one column. Both adjacent cells must be empty and must be inside a grid.

    Limak needs more fun and thus he is going to consider some queries. In each query he chooses some rectangle and wonders, how many way are there to put a single domino inside of the chosen rectangle?

    Input

    The first line of the input contains two integers h and w (1 ≤ h, w ≤ 500) – the number of rows and the number of columns, respectively.

    The next h lines describe a grid. Each line contains a string of the length w. Each character is either '.' or '#' — denoting an empty or forbidden cell, respectively.

    The next line contains a single integer q (1 ≤ q ≤ 100 000) — the number of queries.

    Each of the next q lines contains four integers r1i, c1i, r2i, c2i (1 ≤ r1i ≤ r2i ≤ h, 1 ≤ c1i ≤ c2i ≤ w) — the i-th query. Numbers r1i and c1i denote the row and the column (respectively) of the upper left cell of the rectangle. Numbers r2i and c2i denote the row and the column (respectively) of the bottom right cell of the rectangle.

    Output

    Print q integers, i-th should be equal to the number of ways to put a single domino inside the i-th rectangle.

    Sample test(s)
    Input
    5 8
    ....#..#
    .#......
    ##.#....
    ##..#.##
    ........
    4
    1 1 2 3
    4 1 4 1
    1 2 4 5
    2 5 5 8
    Output
    4
    0
    10
    15
    Input
    7 39
    .......................................
    .###..###..#..###.....###..###..#..###.
    ...#..#.#..#..#.........#..#.#..#..#...
    .###..#.#..#..###.....###..#.#..#..###.
    .#....#.#..#....#.....#....#.#..#..#.#.
    .###..###..#..###.....###..###..#..###.
    .......................................
    6
    1 1 3 20
    2 10 6 30
    2 10 7 30
    2 2 7 7
    1 7 7 7
    1 8 7 8
    Output
    53
    89
    120
    23
    0
    2
    Note

    A red frame below corresponds to the first query of the first sample. A domino can be placed in 4 possible ways.

    题意:输入h,w表示行和列的数目,接下来h行描述一个网格,每一行有一个长度为w的字符串,每个字符要么是'.',要么是'#',分别表示空的和禁止的。

      输入一个q,接下来得q行有4个数,表示一个小网格的左上角的横纵坐标和右下角的横纵坐标。

      输出每个小方格内有几个2个连在一起的空格。

    思路:网格存在gg[MAXN][MAXN]中,用两个二位数组row[MAXN][MAXN]和column[MAXN][MAXN];row[i][j]表示第i行从开始到j这个位置有几个2个连在一起的空格,column[i][j]表示第j列从开始到i这个位置有几个2个连在一起的空格。

    row举例来说,如果gg[i][j]这个位置是'.'并且它前面gg[i][j-1]这个位置也是'.'的话row[i][j]=row[i][j-1]+1;否则的话,row[i][j]=row[i][j-1]。

    要注意越界的问题。

    if(gg[i][j]=='.'&&j>1&&gg[i][j-1]=='.') row[i][j]=row[i][j-1]+1;
    else row[i][j]=row[i][j-1];


    if(gg[i][j]=='.'&&i>1&&gg[i-1][j]=='.') column[i][j]=column[i-1][j]+1;
    else column[i][j]=column[i-1][j];

    #include<iostream>
    #include<cstdio>
    #include<cstring>
    using namespace std;
    char gg[510][510];
    int row[510][510],column[510][510];
    int x1[100010],y1[100010],x2[100010],y2[100010];
    int main()
    {
        int h,w,q;
        scanf("%d %d",&h,&w);
        getchar();
        memset(row,0,sizeof(row));
        memset(column,0,sizeof(column));
        int i,j;
        for(i=1; i<=h; i++)
        {
            for(j=1; j<=w; j++)
            {
                scanf("%c",&gg[i][j]);
                if(gg[i][j]=='.'&&j>1&&gg[i][j-1]=='.') row[i][j]=row[i][j-1]+1;
                else row[i][j]=row[i][j-1];
                if(gg[i][j]=='.'&&i>1&&gg[i-1][j]=='.') column[i][j]=column[i-1][j]+1;
                else column[i][j]=column[i-1][j];
            }
            getchar();
        }
        /*
        for(i=1; i<=h; i++)
        {
            for(j=1; j<=w; j++)
                cout<<row[i][j]<<" ";
            cout<<endl;
        }
        cout<<endl<<endl;
        for(i=1; i<=h; i++)
        {
            for(j=1; j<=w; j++)
                cout<<column[i][j]<<" ";
            cout<<endl;
        }
        */
        scanf("%d",&q);
        for(i=0; i<q; i++)
            scanf("%d%d%d%d",&x1[i],&y1[i],&x2[i],&y2[i]);
        __int64 ans;
        for(i=0; i<q; i++)
        {
            ans=0;
            for(j=x1[i]; j<=x2[i]; j++)
            {
                //cout<<row[j][y2[i]]<<" "<<row[j][y1[i]]<<endl;
                ans+=row[j][y2[i]]-row[j][y1[i]];
            }
            for(j=y1[i]; j<=y2[i]; j++)
            {
                //cout<<column[x2[i]][j]<<" "<<column[x1[i]][j]<<endl;
                ans+=column[x2[i]][j]-column[x1[i]][j];
            }
            cout<<ans<<endl;
        }
    
        return 0;
    }
    I am a slow walker,but I never walk backwards.
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  • 原文地址:https://www.cnblogs.com/GeekZRF/p/5097034.html
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