c/c++语言开发共享洛谷P4462 [CQOI2018]异或序列(莫队)

题意

题目链接

sol

一开始以为k每次都是给出的想了半天不会做。

然而发现读错题了维护个前缀异或和然后直接莫队搞就行，。

#include<bits/stdc++.h>  #define pair pair<int, int> #define mp(x, y) make_pair(x, y) #define fi first #define se second //#define int long long  #define ll long long  #define fin(x) {freopen(#x".in","r",stdin);} #define fout(x) {freopen(#x".out","w",stdout);} using namespace std; const int maxn = 1e6 + 10, mod = 998244353, inf = 1e9 + 10; const double eps = 1e-9; template <typename a, typename b> inline bool chmin(a &a, b b){if(a > b) {a = b; return 1;} return 0;} template <typename a, typename b> inline bool chmax(a &a, b b){if(a < b) {a = b; return 1;} return 0;} template <typename a, typename b> inline ll add(a x, b y) {if(x + y < 0) return x + y + mod; return x + y >= mod ? x + y - mod : x + y;} template <typename a, typename b> inline void add2(a &x, b y) {if(x + y < 0) x = x + y + mod; else x = (x + y >= mod ? x + y - mod : x + y);} template <typename a, typename b> inline ll mul(a x, b y) {return 1ll * x * y % mod;} template <typename a, typename b> inline void mul2(a &x, b y) {x = (1ll * x * y % mod + mod) % mod;} template <typename a> inline void debug(a a){cout << a << 'n';} template <typename a> inline ll sqr(a x){return 1ll * x * x;} 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, q, k, a[maxn], num[maxn], belong[maxn], block; ll now, ans[maxn]; struct query {     int l, r, id;     bool operator < (const query &rhs) const {         return belong[l] == belong[rhs.l] ? r < rhs.r : belong[l] < belong[rhs.l];     } }q[maxn]; void add(int x) {     now += num[k ^ x];     num[x]++; } void delet(int x) {     num[x]--;     now -= num[k ^ x]; } void solve() {     int l = 1, r = 0;     for(int i = 1; i <= q; i++) {         while(r < q[i].r) add(a[++r]);         while(r > q[i].r) delet(a[r--]);         while(l < q[i].l) delet(a[l++]);         while(l > q[i].l) add(a[--l]);         ans[q[i].id] = now;     } } signed main() {     n = read(); q = read(); k = read(); block = sqrt(n);     for(int i = 1; i <= n; i++) a[i] = read() ^ a[i - 1], belong[i] = (i - 1) / block + 1;     for(int i = 1; i <= q; i++) q[i].l = read() - 1, q[i].r = read(), q[i].id = i;     sort(q + 1, q + q + 1);     solve();     for(int i = 1; i <= q; i++) cout << ans[i] << 'n';     return 0; }