Submission #168426

#	Time	Username	Problem	Language	Result	Execution time	Memory
168426		juggernaut	Chessboard (IZhO18_chessboard)	C++14	47 / 100	661 ms	3836 KiB

chessboard

#include<bits/stdc++.h>
#define int long long int
#define fr first
#define sc second
using namespace std;
int n,k,i,j,x,y,res;
pair<int,int>p[100001];
bool a[1001][1001];
int get(int f,int q){
    int cnt=0;
    for(int i=0;i<n;i++)
    for(int j=0;j<n;j++){
        x=i/f;
        y=j/f;
        if(q){
            if((x+y)%2==0){
                if(a[i][j])cnt++;
            }else{
                if(!a[i][j])cnt++;
            }
        }else{
            if((x+y)%2==0){
                if(!a[i][j])cnt++;
            }else{
                if(a[i][j])cnt++;
            }
        }
    }
    return cnt;
}
int get(int f){
    return min(get(f,0),get(f,1));
}
void subtask2(){
    int c[2];
    c[0]=c[1]=0;
    for(i=0;i<k;i++){
        scanf("%lld%lld%lld%lld",&p[i].fr,&p[i].sc,&p[i].fr,&p[i].sc);
        p[i].fr--;
        p[i].sc--;
        c[(p[i].fr+p[i].sc)%2]++;
    }
    res=(n/2)*n+((n%2)*(n/2))-c[1]+c[0];
    res=min(res,(n/2)*n+((n%2)*((n+1)/2))-c[0]+c[1]);
    printf("%lld",res);
    exit(0);
}
main(){
    scanf("%lld%lld",&n,&k);
    if(n>1000)subtask2();
    for(i=0;i<k;i++){
        scanf("%lld%lld%lld%lld",&p[i].fr,&p[i].sc,&p[i].fr,&p[i].sc);
        p[i].fr--;
        p[i].sc--;
        a[p[i].fr][p[i].sc]=1;
    }
    res=get(1);
    for(j=2;j*j<=n;j++){
        if(n%j==0){
            res=min(res,get(j));
            res=min(res,get(n/j));
        }
    }
    printf("%lld",res);
}

Compilation message (stderr)

chessboard.cpp:48:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main(){
      ^
chessboard.cpp: In function 'void subtask2()':
chessboard.cpp:38:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld%lld%lld%lld",&p[i].fr,&p[i].sc,&p[i].fr,&p[i].sc);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
chessboard.cpp: In function 'int main()':
chessboard.cpp:49:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld%lld",&n,&k);
     ~~~~~^~~~~~~~~~~~~~~~~~
chessboard.cpp:52:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld%lld%lld%lld",&p[i].fr,&p[i].sc,&p[i].fr,&p[i].sc);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 8 / 8
• Subtask 3: 15 / 15
• Subtask 4: 16 / 16
• Subtask 5: 0 / 23
• Subtask 6: 0 / 30