Submission #215943

#	Time	Username	Problem	Language	Result	Execution time	Memory
215943		wendy_virgo	XOR Sum (info1cup17_xorsum)	C++14	45 / 100	1692 ms	25584 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;

int n;
int64_t a[N],p10[10];

void Sub1(){
    int ans=0;
    for(int i=1;i<=n;++i){
        for(int j=i;j<=n;++j){
            ans^=(a[i]+a[j]);
        }
    }
    cout<<ans<<'\n';
}

int GetDigit(int64_t x,int k){
    return (x/p10[k-1])%10;
}

void SortByDigit(vector<int64_t> &a,int k){
    vector<int> freq(10);
    for(int i=0;i<a.size();++i){
        freq[GetDigit(a[i],k)]++;
    }
    for(int i=1;i<=9;++i){
        freq[i]+=freq[i-1];
    }
    vector<int64_t> b(a.size());
    for(int i=(int)a.size()-1;i>=0;--i){
        int id=GetDigit(a[i],k);
        b[freq[id]-1]=a[i];
        freq[id]--;
    }
    a=b;
}

void RadixSort(vector<int64_t> &vec){
    for(int i=1;i<=9;++i){
        SortByDigit(vec,i);
    }
    assert(is_sorted(begin(vec),end(vec)));
}

int64_t GetClass(int64_t x,int64_t m,int64_t minVal,int64_t maxVal){
    if(maxVal==minVal){
        return 0;
    }
    return (m-1)*(x-minVal)/(maxVal-minVal);
}

void FlashSort(vector<int64_t>& a){
    int64_t n=a.size();
	if (n>=1){
		int64_t m=max((int64_t)2,(int64_t)(0.43*n));
		int64_t minVal=*min_element(begin(a),end(a));
		int64_t maxVal=*max_element(begin(a),end(a));
		vector<int64_t> L(m,0);
		L[0]=-1;
		for(int i=0;i<n;++i){
            L[GetClass(a[i],m,minVal,maxVal)]++;
		}
		for(int i=1;i<m;++i){
            L[i]+=L[i-1];
		}
		int64_t i=0;
		int64_t k=GetClass(a[0],m,minVal,maxVal);
		int64_t nMove=0;
		while(nMove<n){
            while(i>L[k]){
                i++;
                k=GetClass(a[i],m,minVal,maxVal);
            }
            int64_t tmp=a[i];
            while(i<=L[k]){
                k=GetClass(tmp,m,minVal,maxVal);
                swap(tmp,a[L[k]]);
                L[k]--;
                nMove++;
            }
		}
		for(int k=0;k<m-1;++k){
            for(int i=L[k]+2;i<=L[k+1];++i){
                int64_t x=a[i],j=i;
                while(j>L[k]+1&&a[j-1]>x){
                    a[j]=a[j-1];
                    j--;
                }
                a[j]=x;
            }
		}
	}
	assert(is_sorted(begin(a),end(a)));
}

int Check(int pos){
    int res=0;
    vector<vector<int64_t>> vec(2);
    for(int i=1;i<=n;++i){
        int64_t val=0;
        for(int j=0;j<pos;++j){
            if((a[i]>>j)&1){
                val|=1<<j;
            }
        }
        vec[(a[i]>>pos)&1].push_back(val);
    }
    FlashSort(vec[0]);
    FlashSort(vec[1]);
//    for(int i=0;i<2;++i){
//        sort(begin(vec[i]),end(vec[i]));
//    }
    int ptr=(int)vec[0].size()-1;
    for(int i=0;i<vec[0].size();++i){
        int64_t val=(1<<pos)-vec[0][i];
        while(ptr>=0&&vec[0][ptr]>=val){
            ptr--;
        }
        if(ptr+1<=i){
            res^=(i-(ptr+1)+1)%2;
        }
    }
    ptr=(int)vec[1].size()-1;
    for(int i=0;i<vec[1].size();++i){
        int64_t val=(1<<pos)-vec[1][i];
        while(ptr>=0&&vec[1][ptr]>=val){
            ptr--;
        }
        if(ptr+1<=i){
            res^=(i-(ptr+1)+1)%2;
        }
    }
    ptr=(int)vec[1].size()-1;
    for(int i=0;i<vec[0].size();++i){
        int64_t val=(1<<pos)-vec[0][i];
        while(ptr>=0&&vec[1][ptr]>=val){
            ptr--;
        }
        res^=(ptr+1)%2;
    }
    return res;
}

void Sub2(){
    int64_t ans=0;
    for(int i=0;i<=31;++i){
        if(Check(i)){
            ans+=(int64_t)1<<i;
        }
    }
    cout<<ans;
}

void Gen(){
    srand(time(0));
    freopen("info1cup17_xorsum.inp","w",stdout);
    int n=rand()%5+1;
    cout<<n<<'\n';
    for(int i=1;i<=n;++i){
        cout<<rand()%10+1<<' ';
    }
    exit(0);
}

int main()
{
//    Gen();
//    freopen("info1cup17_xorsum.inp","r",stdin);
//    freopen("info1cup17_xorsum.out","w",stdout);
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cin>>n;
	for(int i=1;i<=n;++i){
        cin>>a[i];
	}
	p10[0]=1;
	for(int i=1;i<=9;++i){
        p10[i]=p10[i-1]*10;
	}
//	Sub1();
	Sub2();
    return 0;
}

Compilation message (stderr)

xorsum.cpp: In function 'void SortByDigit(std::vector<long int>&, int)':
xorsum.cpp:43:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<a.size();++i){
                 ~^~~~~~~~~
xorsum.cpp: In function 'int Check(int)':
xorsum.cpp:134:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<vec[0].size();++i){
                 ~^~~~~~~~~~~~~~
xorsum.cpp:144:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<vec[1].size();++i){
                 ~^~~~~~~~~~~~~~
xorsum.cpp:154:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<vec[0].size();++i){
                 ~^~~~~~~~~~~~~~
xorsum.cpp: In function 'void Gen()':
xorsum.cpp:176:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
     freopen("info1cup17_xorsum.inp","w",stdout);
     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 38 / 38
• Subtask 5: 0 / 23