func_code_string: #include <bits/stdc++.h>   using namespace std;   struct Data {     bool bip;     int a, xora, ha;     int b, xorb, hb;   };   struct dsu {     int n;     bool bip = 1;     vector<int> x, t, h;     vector<Data> memo;     dsu(int nn) {       n = nn;       x.resize(n + 1);       t.resize(n + 1);       h.resize(n + 1);       for (int i = 1; i <= n; i++) {         x[i] = 0;         t[i] = i;         h[i] = 1;       }       bip = 1;     }     int root(int a) {       if (t[a] == a) {         return a;       } else {         return root(t[a]);       }     }     int color(int a) {       if (t[a] == a) {         return x[a];       } else {         return x[a] ^ color(t[a]);       }     }     void unite(int a, int b) {       int f = a;       int s = b;       a = root(a);       b = root(b);       memo.push_back({bip, a, x[a], h[a], b, x[b], h[b]});       if (a == b) {         if (color(f) == color(s)) {           bip = 0;         }         return;       }       if (h[a] > h[b]) {         swap(a, b);       }       h[b] += (h[a] == h[b]);       t[a] = b;       if (color(f) == color(s)) {         x[a] ^= 1;       }     }     void rev() {       Data it = memo.back();       memo.pop_back();       bip = it.bip;       int a, b;       a = it.a;       b = it.b;       t[a] = a;       t[b] = b;       x[a] = it.xora;       x[b] = it.xorb;       h[a] = it.ha;       h[b] = it.hb;     }   };   vector<bool> solve(int n, vector<pair<int, int>> operations) {     int q = (int)operations.size();     for (auto &it : operations) {       if (it.second > it.first) {         swap(it.first, it.second);       }     }     vector<vector<pair<int, int>>> events(4 * q + 7);     function<void(int, int, int, int, int, int, int)> add =         [&](int v, int tl, int tr, int l, int r, int x, int y) {           if (tr < l || r < tl) {             return;           }           if (l <= tl && tr <= r) {             events[v].push_back({x, y});             return;           }           int tm = (tl + tr) / 2;           add(2 * v, tl, tm, l, r, x, y);           add(2 * v + 1, tm + 1, tr, l, r, x, y);         };     map<pair<int, int>, int> last;     set<pair<int, int>> s;     for (int i = 0; i < q; i++) {       pair<int, int> it = operations[i];       if (s.count(it) == 0) {         last[it] = i;         s.insert(it);       } else {         add(1, 0, q - 1, last[it], i - 1, it.first, it.second);         s.erase(it);       }     }     for (auto &it : s) {       add(1, 0, q - 1, last[it], q - 1, it.first, it.second);     }     vector<bool> ret(q);     dsu d(n);     vector<pair<int, int>> now;     function<void(int, int, int)> dfs = [&](int v, int tl, int tr) {       for (auto &it : events[v]) {         now.push_back(it);         d.unite(it.first, it.second);       }       if (tl == tr) {         ret[tl] = d.bip;       } else {         int tm = (tl + tr) / 2;         dfs(2 * v, tl, tm);         dfs(2 * v + 1, tm + 1, tr);       }       for (auto &it : events[v]) {         now.pop_back();         d.rev();       }     };     dfs(1, 0, q - 1);     return ret;   }   int main() {     ios::sync_with_stdio(0);     cin.tie(0);     int n, q;     cin >> n >> q;     vector<pair<int, int>> Operations(q);     for (int i = 0; i < q; i++) {       cin >> Operations[i].first >> Operations[i].second;     }     vector<bool> x = solve(n, Operations);     for (int i = 0; i < q; i++) {       cout << (x[i] ?  YES  :  NO ) <<   n ;     }   }   