Submission #301888

#	Time	Username	Problem	Language	Result	Execution time	Memory
301888		milisav	Monochrome Points (JOI20_monochrome)	C++14	35 / 100	2058 ms	8312 KiB

monochrome

#include<bits/stdc++.h>
#pragma GCC optimize("O3")
#define maxn 1000000
using namespace std;
int n;
long long ans=0;
char s[2*maxn];
int d[2*maxn];
int seg[8*maxn];
void update(int id,int l,int r,int p,int v) {
    if(l==r) {
        seg[id]=v;
        return;
    }
    int m=(l+r)>>1;
    if(p<=m) update(id*2+1,l,m,p,v);
    else update(id*2+2,m+1,r,p,v);
    seg[id]=seg[id*2+1]+seg[id*2+2];
}
int query(int id,int l,int r,int x,int y) {
    if(x<=l && r<=y) return seg[id];
    if(r<x || y<l) return 0;
    int m=(l+r)>>1;
    return query(id*2+1,l,m,x,y)+query(id*2+2,m+1,r,x,y);
}
int l[maxn];
int r[maxn];
int main() {
    scanf("%d",&n);
    scanf("%s",s);
    if(s[0]=='B') {
        for(int i=0;i<2*n;i++) {
            if(s[i]=='B') s[i]='W';
            else s[i]='B';
        }
    }
    for(int i=0;i<n;i++) {
        int cb=0;
        int x=0;
        int y=0;
        long long cans=0;
        int tmp=0;
        while(cb<i || s[y]!='B') {
            if(s[y]=='B') cb++;
            y++;
            if(y==2*n) y=0;
        }
        int k=1;
        l[k]=x;
        r[k]=y;
        d[x]=-k;
        d[y]=k;
        x++;
        while(x<2*n) {
            if(s[x]=='W') {
                k++;
                do {
                    y++;
                    if(y==2*n) y=0;
                } while(s[y]!='B');
                l[k]=min(x,y);
                r[k]=max(x,y);
                d[min(x,y)]=-k;
                d[max(x,y)]=k;
            }
            x++;
        }
        for(int i=0;i<2*n;i++) {
            if(d[i]>0) {
                update(0,0,2*n-1,l[d[i]],0);
                cans+=query(0,0,2*n-1,l[d[i]],r[d[i]]);
            }
            else update(0,0,2*n-1,i,1);
        }
        ans=max(ans,cans);
    }
    printf("%lld",ans);
	return 0;
}

Compilation message (stderr)

monochrome.cpp: In function 'int main()':
monochrome.cpp:42:13: warning: unused variable 'tmp' [-Wunused-variable]
   42 |         int tmp=0;
      |             ^~~
monochrome.cpp:29:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   29 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
monochrome.cpp:30:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   30 |     scanf("%s",s);
      |     ~~~~~^~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 21 / 21
• Subtask 3: 10 / 10
• Subtask 4: 0 / 65