func_code_string: #include <bits/stdc++.h>   using namespace std;   int min(int a, int b) {     if (a < b) return a;     return b;   }   double min(double a, double b) {     if (a < b) return a;     return b;   }   int max(int a, int b) {     if (a > b) return a;     return b;   }   int ABS(int a) {     if (a < 0) return -a;     return a;   }   int parent[100004], h[100005];   void make_set(int v) { parent[v] = v; }   int find_set(int v) {     if (v == parent[v]) return v;     return parent[v] = find_set(parent[v]);   }   void union_sets(int a, int b) {     a = find_set(a);     b = find_set(b);     if (a != b) {       if (h[a] > h[b]) swap(a, b);       parent[b] = a;     }   }   pair<int, int> getCharHash(int p1, int p2, char c) {     return make_pair(p1 * (c -  a ), p2 * (c -  a ));   }   vector<pair<int, int> > p;   int double_area(int x1, int y1, int x2, int y2, int x3, int y3) {     return (x1 - x2) * (y2 + y1) + (x2 - x3) * (y3 + y2) + (x3 - x1) * (y1 + y3);   }   int tree[4000000];   int c[1000004];   int pref_xors[1000004];   int next_pos[1000004];   int pref_unique_xors[1000006];   map<int, int> M;   set<int> uniques;   vector<pair<pair<int, int>, int> > q;   vector<pair<int, int> > ans;   int suf_sum(int l, int r, int nl, int nr, int node) {     if (l == nl && r == nr) {       return tree[node];     }     int m = (nr + nl) / 2;     if (r <= m) {       return suf_sum(l, r, nl, m, node * 2);     }     if (l > m) {       return suf_sum(l, r, m + 1, nr, node * 2 + 1);     }     return suf_sum(l, m, nl, m, node * 2) ^            suf_sum(m + 1, r, m + 1, nr, node * 2 + 1);   }   void update(int l, int r, int node, int pos, int value) {     if (l == r) {       tree[node] ^= value;       return;     }     int m = (l + r) / 2;     if (pos <= m) {       update(l, m, node * 2, pos, value);     } else {       update(m + 1, r, node * 2 + 1, pos, value);     }     tree[node] = tree[node * 2] ^ tree[node * 2 + 1];     return;   }   int XOR(int i, int j) {     if (i == 0) {       return pref_xors[j];     }     return pref_xors[j] ^ pref_xors[i - 1];   }   int main() {     int n;     int p = 1;     scanf( %d , &n);     while (p <= n) p *= 2;     for (int i = 0; i < n; ++i) {       scanf( %d , c + i);       if (i == 0)         pref_xors[0] = c[0];       else         pref_xors[i] = pref_xors[i - 1] ^ c[i];     }     for (int i = n - 1; i >= 0; --i) {       if (M[c[i]]) {         next_pos[i] = M[c[i]];       } else {         next_pos[i] = n;       }       M[c[i]] = i;     }     int m;     scanf( %d , &m);     int a, b;     for (int i = 0; i < m; ++i) {       scanf( %d%d , &a, &b);       a--;       b--;       q.push_back(make_pair(make_pair(a, b), i));     }     sort(q.begin(), q.end());     for (int i = q[0].first.first; i < n; ++i) {       if (i == 0) {         pref_unique_xors[0] = c[0];         uniques.insert(c[0]);       } else {         if (uniques.find(c[i]) != uniques.end()) {           pref_unique_xors[i] = pref_unique_xors[i - 1];         } else {           pref_unique_xors[i] = pref_unique_xors[i - 1] ^ c[i];           uniques.insert(c[i]);         }       }     }     int j = q[0].first.first;     for (int i = 0; i < m; ++i) {       a = q[i].first.first;       b = q[i].first.second;       if (a != j) {         for (int k = j; k < a; ++k) {           update(0, p - 1, 1, next_pos[k], c[k]);         }         j = a;       }       int answer =           XOR(a, b) ^ pref_unique_xors[b] ^ suf_sum(b + 1, p - 1, 0, p - 1, 1);       ans.push_back(make_pair(q[i].second, answer));     }     sort(ans.begin(), ans.end());     for (int i = 0; i < m; ++i) {       printf( %d n , ans[i].second);     }     return 0;   }   