Add some more problems and update TODO list

Codeforces Round 832 (Div. 2)/D. Yet Another Problem.cpp

@@ -0,0 +1,190 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1747/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 0
+
+void solve()
+{
+    int n, q;
+    cin >> n >> q;
+
+    vi a(n);
+    cin >> a;
+
+    vi pref(n + 1);
+    vi zero(n + 1);
+    unordered_map<int, vi> var;
+    unordered_map<int, vi> odd;
+    unordered_map<int, vi> even;
+    rep(i, n) {
+        pref[i + 1] = pref[i] ^ a[i];
+        zero[i + 1] = zero[i] + (a[i] == 0);
+        var[pref[i + 1]].push_back(i);
+        if (i & 1) {
+            odd[pref[i + 1]].push_back(i);
+        } else {
+            even[pref[i + 1]].push_back(i);
+        }
+    }
+
+
+    while (q--) {
+        int l, r;
+        cin >> l >> r;
+        l--, r--;
+
+        if (zero[r + 1] - zero[l] == r - l + 1) {
+            cout << "0\n";
+            continue;
+        }
+
+        if (r - l <= 1) {
+            cout << "-1\n";
+            continue;
+        }
+
+        int xo = pref[r + 1] ^ pref[l];
+        if (xo != 0) {
+            cout << "-1\n";
+            continue;
+        }
+
+        if ((r - l + 1) & 1) {
+            cout << "1\n";
+            continue;
+        }
+
+        auto fds = var.find(pref[r + 1]);
+        if (fds == var.end()) {
+            cout << "-1\n";
+        }
+
+        vi &tmp = fds->second;
+        auto one = lower_bound(all(tmp), l);
+        auto two = lower_bound(all(tmp), r);
+
+        if (two != tmp.begin()) {
+            two--;
+        }
+
+        if ((one != tmp.end() && *one == l) || (two != tmp.end() && *two == r - 1)) {
+            cout << "1\n";
+            continue;
+        }
+
+        if (r & 1) {
+            vi &act = even[pref[r + 1]];
+            auto itr = lower_bound(all(act), l);
+            if (itr == act.end() || *itr > r) {
+                cout << "-1\n";
+                continue;
+            }
+        } else {
+            vi &act = odd[pref[r + 1]];
+            auto itr = lower_bound(all(act), l);
+            if (itr == act.end() || *itr > r) {
+                cout << "-1\n";
+                continue;
+            }
+        }
+
+        cout << "2\n";
+    }
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}