A. Dars Vaqti

#include<iostream>
using namespace std;
int main(){
    int s1, m1, s2, m2;
    char b;
    cin >> s1 >> b >> m1;
    cin >> s2 >> b >> m2;
    int res = (m2 - m1) * 60;
    if(s2 < s1) res += (24 - s1 + s2) * 3600;
    else res += (s2 - s1) * 3600;
    cout << res;
    return 0;
}

B. Behruzbek va Geometriya

#include<iostream>
using namespace std;
int main(){
    int x1, x2 ,x3 ,y1, y2 ,y3;
    cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
    cout.precision(1);
    cout << fixed << abs(1LL * x1 * (y2 - y3) + 1LL * x2 * (y3 - y1) + 1LL * x3 * (y1 - y2)) / 2.0;
    return 0;
}

C. Static Range Sum Queries
 

#include<bits/stdc++.h>
using namespace std;
#define int long long 
vector<int> tree, arr;
#define endl '\n'
const int mod = 1e9 + 7;
void build(int v, int l, int r){
    if(l == r) tree[v] = arr[l - 1];
    else{
        int m = (l + r) / 2;
        build(v * 2, l, m);
        build(v * 2 + 1, m + 1, r);
        tree[v] = tree[v * 2] + tree[v * 2 + 1];
    }
}
int get(int v, int l, int r, int L, int R){
    if(l == L && r == R){
        return tree[v];
    }
    else{
        int m = (l + r) / 2;
        if(L > m) return get(v * 2 + 1, m + 1, r, L, R);
        else if(R <= m) return get(v * 2, l, m, L, R);
        return get(v * 2, l, m, L, m) + get(v * 2 + 1, m + 1, r, m + 1, R);
    }
}
signed main(){
    int n; cin >> n;
    int q; cin >> q;
    arr.resize(n);
    for(int &x : arr) cin >> x;
    tree.resize(4 * n);
    build(1, 1, n);
    for(int i = 0; i < q; i++){
        int l, r;
        cin >> l >> r;
        cout << get(1, 1, n, l, r) << endl;
    }
}

D. Noutbuk va PC 
 

#include<bits/stdc++.h>
using namespace std;
struct BigInt{
    vector<int> digits;
    int sign; 
    void clear_leading_zeros(){
        while(!digits.empty() && digits.back() == 0)
            digits.pop_back();
        if(digits.empty())
            sign = 0;
    }
    BigInt(){
        sign = 0;
    }
    BigInt(long long a){
        *this = BigInt(to_string(a));
    }
    BigInt(string s){
        if(s.empty()){
            cerr << "Son kiritilmadi!\n";
            exit(1);
        }
        if(!isdigit(s[0])){
            if(s[0] == '+'){
                *this = BigInt(s.substr(1));
            }
            else if(s[0] == '-'){
                *this = BigInt(s.substr(1));
                this->sign *= -1;
            }
            else{
                cerr << "Butun son kiritilmadi!\n";
                exit(2);
            }
        }
        else{
            sign = 1;
            for(int i = (int)s.size() - 1; i >= 0; i --){
                if(!isdigit(s[i])){
                    cerr << "Butun son kiritilmadi!\n";
                    exit(3);
                }
                digits.push_back(s[i] - 48);
            }
            clear_leading_zeros();
        }
    }
    BigInt operator -(){
        BigInt res = *this;
        res.sign *= -1;
        return res;
    }
};

istream& operator >>(istream &cin, BigInt &a){
    string s;
    cin >> s;
    a = BigInt(s);
    return cin;
}

ostream& operator <<(ostream &cout, BigInt a){
    if(a.sign == -1) cout << '-';
    if(a.sign == 0) cout << 0;
    for(int i = (int)a.digits.size() - 1; i >= 0; i --)
        cout << a.digits[i];
    return cout;
}

bool operator <(BigInt a, BigInt b){
    if(a.sign != b.sign) return a.sign < b.sign;
    if(a.sign == 0) return false;
    if(a.digits.size() != b.digits.size())
        return a.digits.size() * a.sign < b.digits.size() * b.sign;
    int i = (int)a.digits.size() - 1;
    while(i > 0 && a.digits[i] == b.digits[i]) i --;
    return a.digits[i] * a.sign < b.digits[i] * b.sign;
}

bool operator >(BigInt a, BigInt b){
    return b < a;
}

bool operator <= (BigInt a, BigInt b){
    return !(b < a);
}

bool operator >= (BigInt a, BigInt b){
    return !(a < b);
}

bool operator ==(BigInt a, BigInt b){
    return a.sign == b.sign && a.digits == b.digits;
}

bool operator !=(BigInt a, BigInt b){
    return !(a == b);
}

BigInt operator +(BigInt, BigInt);

BigInt operator -(BigInt a, BigInt b){
    if(a.sign == 0) return -b;
    if(b.sign == 0) return a;
    if(b.sign == -1) return a + -b;
    if(a.sign == -1) return -(-a+b);
    if(a < b) return -(b-a);
    for(int i = 0; i < a.digits.size(); i ++){
        if(b.digits.size() > i)
            a.digits[i] -= b.digits[i];
        if(a.digits[i] < 0){
            a.digits[i] += 10;
            a.digits[i+1] --;
        }
    }
    a.clear_leading_zeros();
    return a;
}
BigInt operator +(BigInt a, BigInt b){
    if(a.sign == 0) return b;
    if(b.sign == 0) return a;
    if(a.sign != b.sign){
        if(a.sign == -1) return b - -a;
        else return a - -b;
    }
    BigInt c;
    c.sign = a.sign;
    int d = 0, s;
    for(int i = 0; i < a.digits.size() || i < b.digits.size(); i ++){
        s = d;
        if(a.digits.size() > i) s += a.digits[i];
        if(b.digits.size() > i) s += b.digits[i];
        c.digits.push_back(s%10);
        d = s / 10;
    }
    if(d > 0) c.digits.push_back(d);
    return c;
}

BigInt operator *(BigInt a, long long b){
    if(b == 0 || a.sign == 0) return 0;
    BigInt res;
    res.sign = a.sign;
    if(b < 0){
        res.sign *= -1;
        b = -b;
    }
    long long d = 0;
    for(int i = 0; i < a.digits.size(); i ++){
        d += a.digits[i] * b;
        res.digits.push_back(d % 10);
        d /= 10;
    }
    while(d > 0){
        res.digits.push_back(d % 10);
        d /= 10;
    }
    return res;
}

BigInt operator /(BigInt a, long long b){
    if(a.sign == 0) return 0;
    if(b == 0){
        cerr << "0 ga bo'lish mumkin emas!\n";
        exit(4);
    }
    BigInt res;
    res.sign = a.sign;
    if(b < 0){
        res.sign = -res.sign;
        b = -b;
    }
    long long q = 0;
    for(int i = (int)a.digits.size() - 1; i >= 0; i --){
        q = q * 10 + a.digits[i];
        res.digits.push_back(q / b);
        q %= b;
    }
    reverse(res.digits.begin(), res.digits.end());
    res.clear_leading_zeros();
    return res;
}

long long operator %(BigInt a, long long b){
    if(a.sign == 0) return 0;
    if(b == 0){
        cerr << "0 ga qoldiqli bo'lish mumkin emas!\n";
        exit(5);
    }
    if(b < 0)
        b = -b;
    
    long long q = 0;
    for(int i = (int)a.digits.size() - 1; i >= 0; i --){
        q = q * 10 + a.digits[i];
        q %= b;
    }
    return q * a.sign;
}

BigInt operator *(BigInt a, BigInt b){
    if(a.sign == 0 || b.sign == 0) return 0;
    BigInt res;
    res.sign = a.sign * b.sign;
    res.digits.resize(a.digits.size() + b.digits.size());
    for(int i = 0; i < a.digits.size(); i ++)
        for(int j = 0; j < b.digits.size(); j ++)
            res.digits[i+j] += a.digits[i] * b.digits[j];
    
    for(int i = 0; i < res.digits.size(); i ++)
        if(res.digits[i] > 9){
            res.digits[i+1] += res.digits[i] / 10;
            res.digits[i] %= 10;
        }
    res.clear_leading_zeros();
    return res;
}
BigInt abs(BigInt a){
    return (a < 0 ? -a : a);
}
int main(){
    BigInt b, p, n;
    cin >> b >> p >> n;
    BigInt ans = (b + p * 8 / 10) - n;
    cout << abs(ans);
}

E. Chiptalar son

n = int(input()) // 2
dp = [[0] * (n * 9 + 1) for i in range(n+1)]
dp[0][0] = 1
for x in range(1, n+1):
    for s in range(x * 9 + 1):
        dp[x][s] = sum(dp[x - 1][max(s - 9, 0): s + 1])
print(sum([x * x for x in dp[n]]))