Submission #215986

#	Time	Username	Problem	Language	Result	Execution time	Memory
215986		wendy_virgo	XOR Sum (info1cup17_xorsum)	C++14	100 / 100	891 ms	23008 KiB

xorsum

#include <bits/stdc++.h>

using namespace std;

template<typename TH>
void _dbg(const char* sdbg, TH h)
{
	cerr << sdbg << " = " << h << "\n";
}

template<typename TH, typename... TA>
void _dbg(const char* sdbg, TH h, TA... t)
{
	while (*sdbg != ',') cerr << *sdbg++;
	cerr << " = " << h << ",";
	_dbg(sdbg + 1, t...);
}

#define db(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#define chkpt cerr << "--- Checkpoint here ---\n";

const int N=1e6+6;

#define int64_t int

int n;
int64_t a[N],b[N],tmp[N],tmpB[N],vec0[N],n0,vec1[N],n1,freq[2];

void Sort(int pos){
    freq[0]=freq[1]=0;
    for(int i=1;i<=n;++i){
        freq[(a[i]>>pos)&(int64_t)1]++;
    }
    freq[1]+=freq[0];
    for(int i=n;i>=1;--i){
        int id=(a[i]>>pos)&(int64_t)1;
        b[freq[id]]=a[i];
        tmpB[freq[id]]=tmp[i];
        if(id==1){
            tmpB[freq[id]]|=1<<pos;
        }
        freq[id]--;
    }
    for(int i=1;i<=n;++i){
        a[i]=b[i];
        tmp[i]=tmpB[i];
    }
}

int Check(int pos){
    int res=0;
    n0=n1=0;
    for(int i=1;i<=n;++i){
        if((a[i]>>pos)&1){
            vec1[n1++]=tmp[i];
        }
        else{
            vec0[n0++]=tmp[i];
        }
    }
    int ptr=n0-1;
    int ptr1=n1-1;
    int ptr2=n1-1;
    for(int i=0;i<max(n0,n1);++i){
        if(i<n0){
            int64_t val=((int64_t)1<<pos)-vec0[i];
            while(ptr>=0&&vec0[ptr]>=val){
                ptr--;
            }
            if(ptr+1<=i){
                res^=(i-(ptr+1)+1)&1;
            }
            int64_t val1=((int64_t)1<<pos)-vec0[i];
            while(ptr1>=0&&vec1[ptr1]>=val1){
                ptr1--;
            }
            res^=(ptr1+1)&1;
        }
        if(i<n1){
            int64_t val2=((int64_t)1<<pos)-vec1[i];
            while(ptr2>=0&&vec1[ptr2]>=val2){
                ptr2--;
            }
            if(ptr2+1<=i){
                res^=(i-(ptr2+1)+1)&1;
            }
        }
    }
    Sort(pos);
    return res;
}

void Sub2(){
    int64_t ans=0;
    for(int i=0;i<=30;++i){
        if(Check(i)){
            ans+=(int64_t)1<<i;
        }
    }
    cout<<ans;
}

inline int ReadInt()
{
    char c;
    int sign = 1;
    for (c = getchar(); c < '0' || c > '9'; c = getchar())
        if (c == '-') sign = -sign;
    int res = c - '0';
    for (c = getchar(); c >= '0' && c <= '9'; c = getchar())
        res = res * 10 + c - '0';
    return res * sign;
}

int32_t main()
{
//    freopen("info1cup17_xorsum.inp","r",stdin);
//    freopen("info1cup17_xorsum.out","w",stdout);
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	n=ReadInt();
	for(int i=1;i<=n;++i){
        a[i]=ReadInt();
	}
	Sub2();
    return 0;
}

• Subtask 1: 7 / 7
• Subtask 2: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 38 / 38
• Subtask 5: 23 / 23