abc098DXor Sum 2(two point)

Posted 2021-01-13 zwfymqz

题意

题目链接

给出一个序列，求出有多少区间满足(A[l] oplus A[l+1] oplus dots oplus A[r] = A[l] + A[l + 1] +dots+ A[r])

Sol

一个区间能满足要求一定是所有bit上最多只有一个1

这玩意儿显然有单调性，two point扫一遍

#include<cstdio>
#define LL long long 
using namespace std;
const int MAXN = 2e5 + 10;
inline int read() {
    char c = getchar(); int x = 0, f = 1;
    while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}
    while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();
    return x * f;
}
int N, a[MAXN];
main() {
    N = read();
    for(int i = 1; i <= N; i++) a[i] = read();
    LL l = 1, sxor = 0, sum = 0, ans = 0;
    for(int i = 1; i <= N; i++) {
        sum += a[i]; sxor ^= a[i];
        while(sxor != sum && (l < i)) 
            sum -= a[l], sxor ^= a[l++];
        ans += i - l + 1;
    }
    printf("%lld", ans);
    return 0;
}