牛客网第二场Jfarm（随机化+二维前缀和）

链接：https://www.nowcoder.com/acm/contest/140/J
来源：牛客网

White Rabbit has a rectangular farmland of n*m. In each of the grid there is a kind of plant. The plant in the j-th column of the i-th row belongs the a[i][j]-th type.
White Cloud wants to help White Rabbit fertilize plants, but the i-th plant can only adapt to the i-th fertilizer. If the j-th fertilizer is applied to the i-th plant (i!=j), the plant will immediately die.
Now White Cloud plans to apply fertilizers T times. In the i-th plan, White Cloud will use k[i]-th fertilizer to fertilize all the plants in a rectangle [x1[i]...x2[i]][y1[i]...y2[i]].
White rabbits wants to know how many plants would eventually die if they were to be fertilized according to the expected schedule of White Cloud.

输入描述:
The first line of input contains  integers n,m,T(n*m<=,T<=)
For the next n lines, each line contains m integers in range[,n*m] denoting the type of plant in each grid.
For the next T lines, the i-th line contains  integers x1,y1,x2,y2,k(<=x1<=x2<=n,<=y1<=y2<=m,<=k<=n*m)
输出描述:
Print an integer, denoting the number of plants which would die.
示例1
输入

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输出

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随机化，避免4=1+3=2+2

让他只有2+2；

#include<cstdio>
#include<algorithm>
#include<cmath>
#include<cstdlib>
#include<ctime>
#include<vector>
using namespace std;
#define ll long long
int n,m,t;
int b[];
ll a[],qw;
vector<ll>g[];
int x,y,q,w,z;
int main()
{
    srand(time());
    scanf("%d%d%d",&n,&m,&t);
    for(int i=;i<=n+;i++)
        g[i].resize(m+);
    for(int i=;i<=n*m;i++)
    {
        a[i]=(ll)rand()*+(ll)rand();
        a[i]=a[i]+(ll)rand()*+(ll)rand();
    }
    for(int i=;i<=n*m;i++)
        scanf("%d",&b[i]);
    while(t--)
    {

        scanf("%d%d%d%d%d",&x,&y,&q,&w,&z);
        g[x][y]+=a[z];
        g[x][w+]-=a[z];
        g[q+][y]-=a[z];
        g[q+][w+]+=a[z];

    }
    int ans=;
    for(int i=;i<=n*m;i++)
    {
        x=i/m+;
        y=i%m;
        if(y==) y=m,x--;
        qw=g[x][y]+=g[x-][y]+g[x][y-]-g[x-][y-];
        if(qw%a[b[i]]) ans++;
    }
    printf("%d",ans);

    return ;
}