# T13
## Khử trùng
```cpp!
#include <bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(nullptr);cout.tie(nullptr)
using namespace std;
string trim(string s) {
for(int i = s.size() - 1; i >= 0; --i){
if(s[i] == ' ') s.erase(s.begin() + i);
}
return s;
}
int main(){
fast();
unordered_set<string> v;
string c;
while(getline(cin , c)){
v.insert(trim(c));
}
for(string d : v){
cout << d << endl;
}
return 0;
}
```
## Giải thích
```cpp!
#include <iostream>
#if 032 == 32
#include <https>
#endif
int main()
{
https://hackmd.io/@HMNhat/t13;
const int x = 123456789;
const int y = 123'456'789;
cout << x - y << endl;
return 0;
}
```
Lí do 1:
```cpp!
#if 032 == 32
#include <https>
#endif
```
Số 0 trước một số biến nó thành 1 hệ số khác (ko phải decimal) nên điều kiện sai, nhánh ko đc biên dịch, ko lỗi.
SỰ THẬT: ```#include <https>``` KO HỀ TỒN TẠI
#IF và #ENDIF chỉ lầ macro tiền xử lí.
Lí do 2:
`https:` đc compiler coi là label dùng trong lệnh `goto label;`
`//hackmd.io/@HMNhat/t13;` là comment
Lí do 3:
`123'456'789`dấu ' dùng để tách số trong C++ => chạy vẫn đc
## Tổng
### 1
```cpp!
#pragma GCC optimize("unroll-loops, O3, avx2")
#include <bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(nullptr);cout.tie(nullptr)
typedef long long ll;
using namespace std;
int main(){
fast();
int n; cin >> n;
ll tong = 0;
for(int i=1; i <= n; ++i){
tong += i;
}
cout << tong << endl;
return 0;
}
```
### 2
```cpp!
#pragma GCC optimize("unroll-loops, O3, avx2")
#include <bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(nullptr);cout.tie(nullptr)
typedef long long ll;
using namespace std;
int main(){
fast();
int n; cin >> n;
ll tong = 0;
for(int i=1; i <= n; ++i){
tong += (ll)(i * i);
}
cout << tong << endl;
return 0;
}
```
### 3
```cpp!
#pragma GCC optimize("unroll-loops, O3, avx2")
#include <bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(nullptr);cout.tie(nullptr)
typedef long long ll;
using namespace std;
int main(){
fast();
int n; cin >> n;
ll tong = 0;
for(int i=1; i <= n; ++i){
tong += (ll)(i * i * i);
}
cout << tong << endl;
return 0;
}
```
### 4
```cpp!
#pragma GCC optimize("unroll-loops, O3, avx2")
#include <bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(nullptr);cout.tie(nullptr)
typedef long long ll;
const ll MOD = 1e9 + 7;
using namespace std;
int main(){
fast();
int n; cin >> n;
ll tong = 0;
for(int i=1; i <= n; ++i){
tong = (tong + i) % MOD;
}
cout << tong << endl;
return 0;
}
```
### 5
```cpp!
#pragma GCC optimize("unroll-loops, O3, avx2")
#include <bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(nullptr);cout.tie(nullptr)
typedef long long ll;
const ll MOD = 1e9 + 7;
using namespace std;
int main(){
fast();
int n; cin >> n;
ll tong = 0;
for(int i=1; i <= n; ++i){
tong = (tong + i * i) % MOD;
}
cout << tong << endl;
return 0;
}
```
### 6
```cpp!
#pragma GCC optimize("unroll-loops, O3, avx2")
#include <bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(nullptr);cout.tie(nullptr)
typedef long long ll;
const ll MOD = 1e9 + 7;
using namespace std;
int main(){
fast();
int n; cin >> n;
ll tong = 0;
for(int i=1; i <= n; ++i){
tong = (tong + i * i * i) % MOD;
}
cout << tong << endl;
return 0;
}
```
# Homework (verdict:accepted):
### https://codeforces.com/problemset/problem/456/A
```cpp!
#include <bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(nullptr);cout.tie(nullptr)
using namespace std;
int main(){
fast();
int b; cin >>b;
vector<pair<int,int>> a(b);
for(int c=0; c < b; c++){
cin >> a[c].first;
cin >> a[c].second;
}
sort(a.begin(), a.end());
for(int c=1; c < b; c++){
if(a[c].second < a[c-1].second){
cout << "Happy Alex" << endl;
return 0;
}
}
cout << "Poor Alex" << endl;
return 0;
}
```
### https://codeforces.com/problemset/problem/478/C
```cpp!
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
ll a, b,c; cin >> a >> b >>c;
cout << min((a + b + c) /3, a+b+c - max({a, b, c})) << endl;
return 0;
}
```
### https://codeforces.com/problemset/problem/348/A
```cpp!
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
ll s =0, m=0;
int a; cin >> a;
for(int i =0; i < a; ++i){
ll n; cin >> n;
s+=n;
m = max(m, n);
}
ll r = (ll)ceil((long double)s / (a -1));
cout << max(m, r) << endl;
return 0;
}
```
### https://codeforces.com/problemset/problem/4/C
```cpp!
#include<bits/stdc++.h>
using namespace std;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
int a; cin >> a;
unordered_map<string, int> m;
for(int i=0; i < a; ++i){
string n; cin >> n;
if(m.find(n) == m.end()){
cout << "OK" << endl;
m[n] = 0;
} else{
m[n]++;
string n2 = n +to_string(m[n]);
cout << n2 << endl;
m[n2] = 0;
};
}
return 0;
}
```
### https://codeforces.com/problemset/problem/25/A
```cpp!
#include<bits/stdc++.h>
using namespace std;
signed main(){
int a, c =0, l=0; cin >> a;
vector<int> v(a);
for(int i = 0; i < a; ++i){
cin >> v[i];
(v[i] % 2 == 0) ? c++ : l++;
}
if(c > l){
for(int i = 0; i < a; ++i){
if(v[i] % 2 != 0){
cout << (i + 1) << endl;
return 0;
}
}
}
else{
for(int i = 0; i < a; ++i){
if(v[i] % 2 == 0){
cout << (i + 1) << endl;
return 0;
}
}
}
return 0;
}
```
### https://codeforces.com/problemset/problem/406/B
```cpp!
#pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(nullptr);cout.tie(nullptr)
using namespace std;
int main(){
fast();
int n=0; cin >> n;
vector<int> a(n);
for(int c =0; c < n; ++c) cin >> a[c];
sort(a.begin(), a.end());
int q = 0; cin >> q;
for(int c =0; c < q; ++c){
int t =0; cin >> t;
cout << upper_bound(a.begin(), a.end(), t) - a.begin() << endl;
}
return 0;
}
```
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