The 14th Jilin Provincial Collegiate Programming Contest

题目

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define fi first
#define se second
#define lson p << 1
#define rson p << 1 | 1
#define ll long long
#define pii pair<int, int>
#define ld long double
const int maxn = 1e6 + 5, inf = 1e18, maxm = 4e4 + 5, base = 37;
const int N = 1e5 + 5;
const int mod = 1e9 + 7;
// const int mod = 998244353;
// const __int128 mod = 212370440130137957LL;
int n, m;int t[maxn];//树状数组维护区间 所有 不同数字 的异或和
int lowbit(int x){return x & -x;
}void add(int x, int k){for(int i = x; i <= n; i += lowbit(i)){t[i] ^= k;}
}
int ask(int x){int res = 0;for(int i = x; i >= 1; i -= lowbit(i)){res ^= t[i];}return res;
}//long long ? maxn ? n? m?
void solve(){ll res = 0;int k, q;cin >> n >> q;vector<int> a(n + 1), lst(n + 1), ans(q + 1), pre(n + 1);for(int i = 1; i <= n; i++){cin >> a[i];pre[i] = pre[i - 1] ^ a[i];}vector<vector<pii>> qry(n + 1);for(int i = 1; i <= q; i++){int l, r;cin >> l >> r;qry[r].pb({l, i});}map<int, int> mp;//数字最后出现的位置for(int i = 1; i <= n; i++){if(mp.count(a[i])){add(mp[a[i]], a[i]);}add(i, a[i]);mp[a[i]] = i;for(auto [l, id] : qry[i]){int r = i;ans[id] = ask(r) ^ ask(l - 1) ^ pre[r] ^ pre[l - 1];}}for(int i = 1; i <= q; i++){cout << ans[i] << '\n';}
}signed main(){ios::sync_with_stdio(0);cin.tie(0);cout << fixed << setprecision(9);int T = 1;// cin >> T;while (T--){solve();}return 0;
}