1393A - Rainbow Dash, Fluttershy and Chess Coloring
Idea: AlFlen
Tutorial
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Solution (74TrAkToR)
#include<bits/stdc++.h>
using namespace std;
main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t, n;
cin >> t;
while (t--) {
cin >> n;
cout << n / 2 + 1 << '\n';
}
return 0;
}
1393B - Applejack and Storages
Idea: RedMachine-74
Tutorial
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Solution (74TrAkToR)
#include<bits/stdc++.h>
using namespace std;
int const MAXN = 1e5 + 5;
int cnt[MAXN];
main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, q, x, cnt2 = 0, cnt4 = 0;
char type;
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> x;
cnt2 -= cnt[x] / 2;
cnt4 -= cnt[x] / 4;
cnt[x]++;
cnt2 += cnt[x] / 2;
cnt4 += cnt[x] / 4;
}
cin >> q;
for (int i = 1; i <= q; ++i) {
cin >> type >> x;
cnt2 -= cnt[x] / 2;
cnt4 -= cnt[x] / 4;
if (type == '+') cnt[x]++;
else cnt[x]--;
cnt2 += cnt[x] / 2;
cnt4 += cnt[x] / 4;
if (cnt4 >= 1 && cnt2 >= 4) cout << "YES" << '\n';
else cout << "NO" << '\n';
}
return 0;
}
1393C - Pinkie Pie Eats Patty-cakes
Idea: RedMachine-74 и lapochka_queen
Tutorial
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Solution (AlFlen)
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100009;
int cnt[MAXN];
vector<int> a;
int n;
bool check(int x) {
for (int i = 1; i <= n; i ++) cnt[i] = 0;
for (int i = 0; i < n; i ++) cnt[a[i]]++;
set<pair<int, int>, greater<pair<int, int>>> ss; //use greater comparator to sort set in descending order
for (int i = 1; i <= n; i ++) {
if (cnt[i] > 0) ss.insert({cnt[i], i});
}
vector<int> b;
for (int i = 0; i < n; i ++) {
if (i >= x && cnt[b[i - x]]) {
ss.insert({cnt[b[i - x]], b[i - x]});
}
if (ss.empty()) return 0;
b.push_back(ss.begin()->second);
ss.erase(ss.begin());
cnt[b.back()]--;
}
return 1;
}
signed main() {
ios :: sync_with_stdio(0);
cin.tie(0);
int ttt;
cin >> ttt;
while (ttt--) {
cin >> n;
a.resize(n);
for (int i = 0; i < n; i ++) {
cin >> a[i];
}
int l = 0, r = n;
while (r - l > 1) {
int m = (r + l) / 2;
if (check(m)) {
l = m;
}
else {
r = m;
}
}
cout << l - 1 << "\n";
}
return 0;
}
Idea: RedMachine-74
Tutorial
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Solution (74TrAkToR)
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int const maxn = 2005;
char a[maxn][maxn];
int cnt_up[maxn][maxn], cnt_down[maxn][maxn], L[maxn], R[maxn];
main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, m;
cin >> n >> m;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j) cin >> a[i][j];
}
ll ans = 0;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j) {
if (i != 1 && a[i][j] == a[i - 1][j]) cnt_up[i][j] = cnt_up[i - 1][j] + 1;
else cnt_up[i][j] = 0;
}
}
for (int i = n; i >= 1; --i) {
for (int j = 1; j <= m; ++j) {
if (i != n && a[i][j] == a[i + 1][j]) cnt_down[i][j] = cnt_down[i + 1][j] + 1;
else cnt_down[i][j] = 0;
}
}
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j) {
int go = j;
while (go <= m && a[i][j] == a[i][go]) go++;
go--;
for (int pos = j; pos <= go; ++pos) {
if (pos == j) L[pos] = pos;
else {
L[pos] = max(L[pos - 1], pos - min(cnt_up[i][pos], cnt_down[i][pos]));
}
}
j = go;
}
for (int j = m; j >= 1; --j) {
int go = j;
while (go >= 1 && a[i][j] == a[i][go]) go--;
go++;
for (int pos = j; pos >= go; --pos) {
if (pos == j) R[pos] = pos;
else {
R[pos] = min(R[pos + 1], pos + min(cnt_up[i][pos], cnt_down[i][pos]));
}
}
j = go;
}
for (int j = 1; j <= m; ++j) {
ans += (ll)min(j - L[j] + 1, R[j] - j + 1);
}
}
cout << ans << '\n';
return 0;
}
1393E2 - Twilight and Ancient Scroll (harder version)
Idea: AlFlen
Tutorial
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Solution (74TrAkToR)
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int const maxn = 1e5 + 5, maxc = 1e6 + 5;
ll mod[2], P[2], p[2][maxc], rev_P[2];
vector < ll > h[2][maxn];
vector < int > sorted[maxn];
string s[maxn];
int nxt[maxc];
int a[maxc], dp[2][maxc], inf = 1e9 + 7;
int MOD = 1e9 + 7;
ll st(ll x, int y, int ok) {
if (y == 0) return 1;
if (y % 2 == 0) {
ll d = st(x, y / 2, ok);
return d * d % mod[ok];
}
return x * st(x, y - 1, ok) % mod[ok];
}
inline char get_c(int i, int x, int numb) {
if (numb < x) return s[i][numb];
if (numb + 1 < (int)s[i].size()) return s[i][numb + 1];
return ' ';
}
inline ll get_hash(int t, int i, int x, int len) {
if (len < x) return h[t][i][len];
return (h[t][i][x] + (h[t][i][len + 1] - h[t][i][x + 1] + mod[t]) * rev_P[t]) % mod[t];
}
inline pair < ll, ll > get_h(int i, int x, int len) {
return {get_hash(0, i, x, len), get_hash(1, i, x, len)};
}
inline int check(int i, int x, int j, int y) {
int len1 = (int)s[i].size(), len2 = (int)s[j].size();
if (x != len1) len1--;
if (y != len2) len2--;
int lef = 0, righ = min(len1, len2) + 1;
while (righ - lef > 1) {
int mid = (righ + lef) / 2;
if (get_h(i, x, mid) == get_h(j, y, mid)) lef = mid;
else righ = mid;
}
return get_c(i, x, lef) >= get_c(j, y, lef);
}
main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
mod[0] = 1e9 + 7, mod[1] = 1e9 + 9, P[0] = 29, P[1] = 31, rev_P[0] = st(P[0], mod[0] - 2, 0), rev_P[1] = st(P[1], mod[1] - 2, 1);
p[0][0] = 1, p[1][0] = 1;
for (int i = 1; i < maxc; ++i) {
for (int j = 0; j <= 1; ++j) p[j][i] = p[j][i - 1] * P[j] % mod[j];
}
int n;
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> s[i];
for (int j = 0; j <= 1; ++j) {
h[j][i].push_back(0);
for (int pos = 0; pos < (int)s[i].size(); ++pos) {
h[j][i].push_back((h[j][i][pos] + p[j][pos] * (s[i][pos] - 'a' + 1)) % mod[j]);
}
}
nxt[(int)s[i].size() - 1] = (int)s[i].size() - 1;
for (int pos = (int)s[i].size() - 2; pos >= 0; --pos) {
if (s[i][pos] != s[i][pos + 1]) nxt[pos] = pos + 1;
else nxt[pos] = nxt[pos + 1];
}
int l = 0, r = (int)s[i].size() - 1;
for (int j = 0; j < (int)s[i].size(); ++j) {
if (s[i][nxt[j]] <= s[i][j]) a[l++] = j;
else a[r--] = j;
}
for (int j = 0; j < (int)s[i].size(); ++j) {
sorted[i].push_back(a[j]);
if (a[j] == (int)s[i].size() - 1) sorted[i].push_back((int)s[i].size());
}
}
for (int i = 0; i <= (int)s[1].size(); ++i) {
dp[0][i] = 1;
}
for (int i = 2; i <= n; ++i) {
int oks = (i - 1) % 2, ptr = 0, sum = 0, cur = -1;
for (auto key : sorted[i]) {
cur++;
while (ptr < (int)sorted[i - 1].size() && check(i, key, i - 1, sorted[i - 1][ptr])) {
sum += dp[(1^oks)][ptr];
if (sum >= MOD) sum -= MOD;
ptr++;
}
dp[oks][cur] = sum;
}
}
int ans = 0;
for (int i = 0; i <= (int)s[n].size(); ++i) {
ans += dp[(n - 1) % 2][i];
if (ans >= MOD) ans -= MOD;
}
cout << ans << '\n';
return 0;
}