Submission #141204

#	Time	Username	Problem	Language	Result	Execution time	Memory
141204		meatrow	XOR Sum (info1cup17_xorsum)	C++17	100 / 100	650 ms	11160 KiB

xorsum

#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,tune=native")
//#pragma GCC optimize ("unroll-loops")
#include <bits/stdc++.h>

using namespace std;

/** Interface */
 
inline int readChar();
template <class T = int> inline T readInt();
template <class T> inline void writeInt( T x, char end = 0 );
inline void writeChar( int x );
inline void writeWord( const char *s );
 
/** Read */
 
static const int buf_size = 4096;
 
inline int getChar() {
    static char buf[buf_size];
    static int len = 0, pos = 0;
    if (pos == len)
        pos = 0, len = fread(buf, 1, buf_size, stdin);
    if (pos == len)
        return -1;
    return buf[pos++];
}
 
inline int readChar() {
    int c = getChar();
    while (c <= 32)
        c = getChar();
    return c;
}
 
template <class T>
inline T readInt() {
    int s = 1, c = readChar();
    T x = 0;
    if (c == '-')
        s = -1, c = getChar();
    while ('0' <= c && c <= '9')
        x = x * 10 + c - '0', c = getChar();
    return s == 1 ? x : -x;
}
 
/** Write */
 
static int write_pos = 0;
static char write_buf[buf_size];
 
inline void writeChar( int x ) {
    if (write_pos == buf_size)
        fwrite(write_buf, 1, buf_size, stdout), write_pos = 0;
    write_buf[write_pos++] = x;
}
 
template <class T>
inline void writeInt( T x, char end ) {
    if (x < 0)
        writeChar('-'), x = -x;
 
    char s[24];
    int n = 0;
    while (x || !n)
        s[n++] = '0' + x % 10, x /= 10;
    while (n--)
        writeChar(s[n]);
    if (end)
        writeChar(end);
}
 
inline void writeWord( const char *s ) {
    while (*s)
        writeChar(*s++);
}
 
struct Flusher {
    ~Flusher() {
        if (write_pos)
            fwrite(write_buf, 1, write_pos, stdout), write_pos = 0;
    }
} flusher;

using ll = long long;
using ld = long double;

const int M = 30;
const int N = 1e6;

int a[N];
int k[2];
int y[2][N];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n = readInt();
    for (int i = 0; i < n; i++) {
        a[i] = readInt();
    }
    int ans = 0;
    int pw = 1;
    for (int b = 0; b < M; b++) {
        int q = (pw << 1) - 1;
        int kek = 0;
        k[0] = k[1] = 0;
        for (int i = 0; i < n; i++) {
            y[(a[i] >> b) & 1][k[(a[i] >> b) & 1]++] = a[i];
        }
        int p = 0;
        for (int i = 0; i < 2; i++) {
            memcpy(a + p, y[i], sizeof(int) * k[i]);
            p += k[i];
        }
        int it1 = n - 1;
        int it2 = n - 1;
        int it3 = n - 1;
        for (int i = 0; i < n; i++) {
            int t = a[i] & q;
            while (it1 >= 0 && (a[it1] & q) >= pw - t) {
                it1--;
            }
            while (it2 >= 0 && (a[it2] & q) > q - t) {
                it2--;
            }
            while (it3 >= 0 && (a[it3] & q) >= 3 * pw - t) {
                it3--;
            }
            (kek += max(0, min(it2, i) - it1)) &= 1;
            if (t & pw) {
                (kek += max(0, i - it3)) &= 1;
            }
        }
        if (kek) {
            ans += pw;
        }
        pw <<= 1;
    }
    writeInt(ans);
    return 0;
}

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