[题解]LuoGu4462：[CQOI2018]异或序列

原题传送门
首先，区间异或就等于两个前缀异或和
即[l,r]=[1,r] ^ [1,l - 1]
把问题转换成两个值的异或啦，开个桶就行了

处理询问果断莫队好吧

Code：

#include <bits/stdc++.h>
#define maxn 100010
using namespace std;
int n, m, k, a[maxn], sum, cnt[maxn], ans[maxn];
struct ques{
	int l, r, pos, id;
}q[maxn];

inline int read(){
	int s = 0, w = 1;
	char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') w = -1;
	for (; isdigit(c); c = getchar()) s = (s << 1) + (s << 3) + (c ^ 48);
	return s * w;
}

bool cmp(ques x, ques y){ return x.pos == y.pos ? x.r < y.r : x.pos < y.pos; }
void add(int x){ sum += cnt[k ^ a[x]]; ++cnt[a[x]]; }
void del(int x){ --cnt[a[x]]; sum -= cnt[k ^ a[x]]; }

int main(){
	n = read(), m = read(), k = read();
	for (int i = 1; i <= n; ++i){
		a[i] = read();
		a[i] ^= a[i - 1];
	}
	int block = sqrt(n);
	for (int i = 1; i <= m; ++i){
		q[i].l = read(), q[i].r = read(); --q[i].l;
		q[i].pos = q[i].l / block, q[i].id = i;
	}
	sort(q + 1, q + 1 + m, cmp);
	int l = 0, r = 0; add(0);
	for (int i = 1; i <= m; ++i){
		for (; r < q[i].r; add(++r));
		for (; r > q[i].r; del(r--));
		for (; l < q[i].l; del(l++));
		for (; l > q[i].l; add(--l));
		ans[q[i].id] = sum;
	}
	for (int i = 1; i <= m; ++i) printf("%d\n", ans[i]);
	return 0;
}