Random stuff

Author: dolphingarlic

CCO/CCC 20-searching/one-hash.cpp

@@ -0,0 +1,43 @@
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+const ll P1 = 9973, P2 = 69420, M1 = 1e9 + 9, M2 = 998244353;
+
+int freq_target[26], freq_curr[26];
+string s, t;
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    cin >> s >> t;
+    if (s.size() > t.size()) return cout << 0, 0;
+
+    set<pair<ll, ll>> good;
+    ll poly1 = 0, poly2 = 0, p_pow1 = 1, p_pow2 = 1;
+    for (int i = 0; i < s.size(); i++) {
+        freq_target[s[i] - 'a']++, freq_curr[t[i] - 'a']++;
+        poly1 = (poly1 * P1 + (t[i] - 'a')) % M1;
+        poly2 = (poly2 * P2 + (t[i] - 'a')) % M2;
+        p_pow1 = p_pow1 * P1 % M1;
+        p_pow2 = p_pow2 * P2 % M2;
+    }
+    {
+        bool match = true;
+        for (int j = 0; j < 26; j++) match &= freq_curr[j] == freq_target[j];
+        if (match) good.insert({poly1, poly2});
+    }
+
+    for (int i = s.size(); i < t.size(); i++) {
+        freq_curr[t[i] - 'a']++;
+        freq_curr[t[i - s.size()] - 'a']--;
+        poly1 = (poly1 * P1 - p_pow1 * (t[i - s.size()] - 'a') % M1 + (t[i] - 'a') + M1) % M1;
+        poly2 = (poly2 * P2 - p_pow2 * (t[i - s.size()] - 'a') % M2 + (t[i] - 'a') + M2) % M2;
+        
+        bool match = true;
+        for (int j = 0; j < 26; j++) match &= freq_curr[j] == freq_target[j];
+        if (match) good.insert({poly1, poly2});
+    }
+
+    cout << good.size() << '\n';
+    return 0;
+}

CCO/CCC 20-searching/two-hash.cpp

@@ -0,0 +1,52 @@
+#include <bits/stdc++.h>
+typedef long long ll;
+using namespace std;
+
+const ll P1 = 9973, P2 = 69420, M1 = 1e9 + 9, M2 = 998244353;
+
+ll inv(ll base, ll MOD) {
+    ll ans = 1, expo = MOD - 2;
+    while (expo) {
+        if (expo & 1) ans = ans * base % MOD;
+        expo >>= 1;
+        base = base * base % MOD;
+    }
+    return ans;
+}
+
+string n, h;
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    cin >> n >> h;
+    if (n.size() > h.size()) return cout << 0, 0;
+
+    set<pair<ll, ll>> good;
+    ll n_hsh1 = 1, h_hsh1 = 1, n_hsh2 = 1, h_hsh2 = 1;
+    ll poly1 = 0, poly2 = 0, p_pow1 = 1, p_pow2 = 1;
+    for (int i = 0; i < n.size(); i++) {
+        n_hsh1 = n_hsh1 * (P1 + n[i] - 'a') % M1;
+        n_hsh2 = n_hsh2 * (P2 + n[i] - 'a') % M2;
+        h_hsh1 = h_hsh1 * (P1 + h[i] - 'a') % M1;
+        h_hsh2 = h_hsh2 * (P2 + h[i] - 'a') % M2;
+
+        poly1 = (poly1 * P1 + (h[i] - 'a')) % M1;
+        poly2 = (poly2 * P2 + (h[i] - 'a')) % M2;
+        p_pow1 = p_pow1 * P1 % M1;
+        p_pow2 = p_pow2 * P2 % M2;
+    }
+    if (n_hsh1 == h_hsh1 && n_hsh2 == h_hsh2) good.insert({poly1, poly2});
+
+    for (int i = n.size(); i < h.size(); i++) {
+        h_hsh1 = h_hsh1 * inv(P1 + h[i - n.size()] - 'a', M1) % M1 * (P1 + h[i] - 'a') % M1;
+        h_hsh2 = h_hsh2 * inv(P2 + h[i - n.size()] - 'a', M2) % M2 * (P2 + h[i] - 'a') % M2;
+
+        poly1 = (poly1 * P1 - p_pow1 * (h[i - n.size()] - 'a') % M1 + (h[i] - 'a') + M1) % M1;
+        poly2 = (poly2 * P2 - p_pow2 * (h[i - n.size()] - 'a') % M2 + (h[i] - 'a') + M2) % M2;
+        
+        if (n_hsh1 == h_hsh1 && n_hsh2 == h_hsh2) good.insert({poly1, poly2});
+    }
+
+    cout << good.size() << '\n';
+    return 0;
+}

IOI/IOI 04-empodia.cpp

@@ -22,7 +22,6 @@ again, so we pop it from the stack
 */
 
 #include <bits/stdc++.h>
-#define FOR(i, x, y) for (int i = x; i < y; i++)
 using namespace std;
 
 int a[2000000], le[2000000], gr[2000000];
@@ -33,12 +32,12 @@ int main() {
     int n;
     map<int, stack<int>> mp;
     cin >> n;
-    FOR(i, 0, n) {
+    for (int i = 0; i < n; i++) {
         cin >> a[i];
         mp[a[i] - i].push(i);
     }
     stack<int> stck;
-    FOR(i, 0, n) {
+    for (int i = 0; i < n; i++) {
         while (stck.size() && a[stck.top()] < a[i]) stck.pop();
         if (stck.size())
             gr[i] = stck.top();

POI/POI 11-lightning_conductor.cpp

@@ -1,8 +1,4 @@
 #include <bits/stdc++.h>
-#pragma GCC optimize("O3")
-#define FOR(i, x, y) for (ll i = x; i < y; i++)
-#define MOD 1000000007
-typedef long long ll;
 using namespace std;
 
 int n, h[500000], dp1[500000], dp2[500000];
@@ -14,7 +10,7 @@ double slope(int j, int k) {
 
 void solve(int dp[]) {
     deque<int> q;
-    FOR(i, 0, n) {
+    for (int i = 0; i < n; i++) {
         // Keep the queue monotone
         if (!i || h[q.back()] < h[i]) {
             while ((q.size() > 0 &&
@@ -33,12 +29,13 @@ int main() {
     iostream::sync_with_stdio(false);
     cin.tie(0);
     cin >> n;
-    FOR(i, 0, n) cin >> h[i];
+    for (int i = 0; i < n; i++) cin >> h[i];
 
     solve(dp1);
-    FOR(i, 0, n / 2) swap(h[i], h[n - 1 - i]);
+    for (int i = 0; i < n / 2; i++) swap(h[i], h[n - 1 - i]);
     solve(dp2);
 
-    FOR(i, 0, n) cout << max(dp1[i], dp2[n - 1 - i]) - h[n - 1 - i] << '\n';
+    for (int i = 0; i < n; i++)
+        cout << max(dp1[i], dp2[n - 1 - i]) - h[n - 1 - i] << '\n';
     return 0;
 }

POI/POI 17-sabotage.cpp

@@ -1,7 +1,5 @@
 #include <bits/stdc++.h>
-#pragma GCC optimize("O3")
 #define FOR(i, x, y) for (int i = x; i < y; i++)
-#define MOD 1000000007
 typedef long long ll;
 using namespace std;