Just [Array]

Anower HossainAnower Hossain
7 min read

ICPC Assiut University Community Newcomers Training, Do Your Best

A. Summation

void solve() {
    int n; cin>>n;
    ll arr[n];
    ll sum = 0;
    for(int i=0; i<n; i++) {
        cin >> arr[i];
        sum += arr[i];
    }
    cout<< abs(sum) << '\n';
}

B. Searching

void solve() {
    int n; cin >> n;
    ll arr[n];
    for(int i=0; i<n; i++) {
        cin>> arr[i];
    }
    int x; cin >> x;
    for(int i=0; i<n; i++) {
        if(arr[i]==x) {
            cout<< i << '\n';
            return;
        }
    }
    cout<< -1 << '\n';
}

C. Replacement

void solve() {
    int n; cin >> n;
    ll arr[n];
    for(int i=0; i<n; i++) {
        cin>> arr[i];
    }
    for(int i=0; i<n; i++) {
        if (arr[i] > 0) {
            arr[i] = 1;
        } else if (arr[i] < 0){
            arr[i] = 2;
        } else {
            arr[i] = 0;
        }
    }

    for(int i=0; i<n; i++) {
        cout<< arr[i] << ' ';
    }
    cout<< '\n';
}

D. Positions in array

void solve() {
    int n; cin >> n;
    ll arr[n];
    for(int i=0; i<n; i++) {
        cin>> arr[i];
    }
    for(int i=0; i<n; i++) {
        if(arr[i] <= 10) { 
            cout<< "A[" << i << "] = " << arr[i] << '\n';
        }
    }
}

E. Lowest Number

oid solve() {
    int n; cin >> n;
    ll arr[n];
    for(int i=0; i<n; i++) {
        cin>> arr[i];
    }
    int mn = INT_MAX, idx = -1;
    for(int i=0; i<n; i++) {
        if (arr[i] < mn) {
            mn = arr[i];
            idx = i;
        } 
    }
    cout<< mn << " " << (idx+1) << '\n';
}

F. Reversing

void solve() {
    int n; cin >> n;
    ll arr[n];
    for(int i=0; i<n; i++) {
        cin>> arr[i];
    }
    for(int i=n-1; i>=0; i--) {
        cout<< arr[i] << ' ';
    }
    cout<< '\n';
}

G. Palindrome Array

void solve() {
    int n; cin >> n;
    ll arr[n];
    for(int i=0; i<n; i++) {
        cin>> arr[i];
    }
    bool is_palindrome = true;
    for(int i=0; i<n/2; i++) {
        if(arr[i] != arr[n-i-1]) {
            is_palindrome = false;
            break;
        }
    }
    cout<< (is_palindrome ? "YES\n" : "NO\n");
}

H. Sorting

void solve() {
    int n; cin >> n;
    ll arr[n];
    for(int i=0; i<n; i++) {
        cin>> arr[i];
    }
    sort(arr, arr+n);
    for(int i=0; i<n; i++) {
        cout<< arr[i] << ' ';
    }
    cout<< '\n';


}

I. Smallest Pair

void solve() {
    int n; cin>>n;
    int arr[n];
    for(int i=0; i<n; i++) cin>>arr[i];

    int mn_val = INT_MAX;
    for(int i=0; i<n; i++) {
        for (int j=i+1; j<n; j++) {
            int cal = arr[i] + arr[j] + j - i;
            mn_val = min(mn_val, cal);
        }
    }
    cout<< mn_val << '\n';
}

J. Lucky Array

void solve()
{
    int n; cin>>n;
    vector<int> a(n);
    for(int i=0; i<n; i++) cin>>a[i];

    int mn = *min_element(a.begin(), a.end());
    int cnt = count(a.begin(), a.end(), mn);

    if(cnt%2 == 1) cout<<"Lucky\n";
    else cout<<"Unlucky\n";
}

K. Sum Digits

void solve()
{
    int n; cin>>n;
    string s; cin>>s;
    int digit_sum = 0;
    for(char digit : s) {
        digit_sum += digit - '0'; 
    }
    cout<< digit_sum <<'\n';

}

L. Max Subarray


void sub_arr(int n, vector<int> arr) {
    vector<int> mx_sub_arr;

    for(int i=0; i<n; i++) {
        int curr_mx_ele = arr[i];
        for(int j=i; j<n; j++) {
            curr_mx_ele = max(curr_mx_ele, arr[j]);
            // cout<< curr_mx_ele<< ' ';
            mx_sub_arr.push_back(curr_mx_ele);
        }
    }

    for(int mx_val : mx_sub_arr) {
        cout<< mx_val << " ";
    }
    cout<<'\n';
}

M. Replace MinMax

void solve() {
    int n; cin>>n; 
    vector<int> arr(n);
    for(int i=0; i<n; i++) cin>>arr[i];

    int mx_idx = max_element(arr.begin(), arr.end()) - arr.begin(); 
    int mn_idx = min_element(arr.begin(), arr.end()) - arr.begin(); 

    swap(arr[mn_idx], arr[mx_idx]);

    for(int num: arr) {
        cout << num << " ";
    }
    cout<< '\n';

}

N. Check Code

main{
    int a,b; // 3 3
    cin>>a>>b;
    string code; 
    cin>>code;
    if(a+b+1 != code.size()){
        cout<<"No"<<endl;
        return 0;
    }
    if(code[a] != '-'){
        cout<<"No"<<endl;
        return 0;
    }
    int counter = 0;
    for(int i=0;i<code.size();i++){
        if(code[i] >= 48 && code[i] <=57 && i != a){
            counter++; // 6
        }
    }
    if(counter == a+b){
        cout<<"Yes"<<endl;
    } else {
        cout<<"No"<<endl;
    }

}

O. Fibonacci

ll fibo(int n) {
    if(n == 1) return 0;
    if(n == 2) return 1;

    ll p1 = 0, p2 = 1, curr;
    for(int i=3; i<=n; i++) {
        curr = p1 + p2;
        p1 = p2;
        p2 = curr;
    }
    return p2;
}

P. Minimize Number

void solve() {
    int n; cin>>n; 
    int arr[n], mn = INT_MAX;

    for(int i=0; i<n; i++) {
        cin>>arr[i];
        int c=0;
        while(arr[i]%2 == 0 and arr[i]>0) {
            c++;
            arr[i]/=2;
        }
        mn = min(mn, c);
    }
    cout<< mn;

}

Q. Count Subarrays (Optimize Solution -> O(N)

void sub_array(int n, vector<int> arr) {
    int c=0, len = 1; 
    for(int i=1; i<n; i++) {
        if(arr[i] >= arr[i-1]) {
            len++;
        } else {
            c += (len * (len+1) / 2);
            len = 1;
        }
    }
    c += (len * (len+1) / 2);
    cout<< c <<'\n';
}

Q. Count Subarrays (Simple Solution -> O(N^2))

void sub_array_2(int n, vector<int> arr) { // O(N^2)
    int c = 0;
    for(int i=0; i<n; i++) {
        c++;
        for(int j=i+1; j<n; j++) {
            if(arr[j] >= arr[j-1]) {
                c++;
            } else break;
        }
    }
    cout << c << '\n';
}

R. Permutation with arrays

void solve(int tc = 0) {
    int n; cin>>n;
    vector<int> a(n), b(n);
    for(int i=0; i<n; i++) cin>>a[i]; 
    for(int i=0; i<n; i++) cin>>b[i]; 

    sort(a.begin(), a.end());
    sort(b.begin(), b.end());
    cout<< ((a == b) ? "yes":"no" ); 
}

S. Search In Matrix

void solve(int tc = 0) {
    int n,m; cin>>n>>m;
    int mat[n][m];
    for(int i=0; i<n; i++) {
        for(int j=0; j<m; j++) {
            cin>> mat[i][j];
        }
    }
    int x; cin>>x;
    bool found = false;
    for(int i=0; i<n; i++) {
        for(int j=0; j<m; j++) {
            if(mat[i][j] == x) {
                found = true;
                break; 
            }
        }
        if(found) break;
    }
    cout<< ((found) ? "will not take number\n":"will take number\n");
}

T. Matrix

void solve(int tc = 0) {
    int n; cin>>n;
    int mat[n][n];
    for(int i=0; i<n; i++) {
        for(int j=0; j<n; j++) {
            cin>> mat[i][j];
        }
    }
    int P_sum = 0;
    int S_sum = 0;
    for(int i=0; i<n; i++) {
        P_sum += mat[i][i];
        S_sum += mat[i][n-1-i];
    }
    cout<< abs(P_sum - S_sum) << '\n';
}

U. Is B a subsequence of A ?

void solve(int tc = 0) {
    int n, m; cin>>n>>m;
    vector<int> a(n), b(m);
    for(int i=0; i<n; i++) cin>> a[i];
    for(int i=0; i<m; i++) cin>> b[i];
    int i=0, j=0;
    while(i < n and j < m) {
        if(a[i] == b[j]) {
            j++;
        }; 
        i++;
    }
    cout << ((j==m) ? "YES\n":"NO\n");
}

V. Frequency Array

void solve(int tc = 0) {
    int n,m; cin>>n>>m;
    vector<int> a(n), freq(m+1);
    for(int i=0; i<n; i++) {
        cin>>a[i];
        freq[a[i]]++;
    }
    for(int i=1; i<=m; i++) {
        cout<< freq[i] << '\n';
    }
}

W. Mirror Array

void solve(int tc = 0) {
    int n,m; cin>>n>>m;
    vector<vector<int>> mat(n, vector<int>(m+1));
    for(int i=0; i<n; i++) {
        for(int j=0; j<m; j++) {
            cin>> mat[i][j];
        }
    }
    for(int i=0; i<n; i++) {
        for(int j=m-1; j>=0; j--) {
            cout<< mat[i][j] <<" ";
        }
        cout<< '\n';
    }
}

X. 8 Neighbors

void solve(int tc = 0) {
    int n,m; cin>>n>>m;
    // vector<vector<char>> mat(n, vector<char>(m+1));
    char mat[n][m];
    for(int i=0; i<n; i++) {
        for(int j=0; j<m; j++) {
            cin>> mat[i][j];
        }
    }

    int x,y; cin>>x>>y;
    // 0 - Based
    x--,y--;

    // Possible 8 direction X,Y 
    // vector<pair<int, int>> directions
    int dxy[8][2] = {
        {-1, 0}, {1, 0}, {0, 1}, {0, -1},
        {-1, -1}, {-1, 1}, {1, -1}, {1, 1}
    };

    for(int i=0; i<8; i++) {
        int nx = x + dxy[i][0];
        int ny = y + dxy[i][1];

        if(nx >= 0 and nx < n and ny >= 0 and ny < m and mat[nx][ny] != 'x') {
            cout << "no\n";
            return;
        }
    }
    cout << "yes\n";
}

Y. Range sum query

void solve(int tc = 0) {
    ll n,q; cin>>n>>q;
    ll a[n];
    for(int i=0; i<n; i++) cin>>a[i];

    ll pre[n];
    pre[0] = a[0];
    for(int i=1; i<n; i++) {
        pre[i] = a[i] + pre[i-1];
    }

    while(q--) {
        ll l,r; cin>>l>>r;
        l--;
        r--;
        ll sum_res;
        if(l==0) {
            sum_res = pre[r];
        } else {
            sum_res = pre[r] - pre[l-1];
        }
        cout<< sum_res << '\n';
    }
}

Z. Binary Search

bool binary_search(int a[], int n, int x) {
    int l = 0, r = n - 1;

    while(l <= r) {
        int mid = l + (r - l) / 2;
        if(a[mid] == x) {
            return true;
        } else if(a[mid] < x) {
            l = mid + 1;
        } else {
            r = mid - 1;
        }
    }
    return false;
}


void solve(int tc = 0) {
    int n,q; cin>>n>>q;
    int a[n];
    for(int i=0; i<n; i++) cin>>a[i];

    sort(a, a + n);
    while(q--) {
        int x; cin>>x;
        if(binary_search(a, n, x)) {
            cout <<  "found\n";
        } else {
            cout <<  "not found\n";
        }
    }
}
0
Subscribe to my newsletter

Read articles from Anower Hossain directly inside your inbox. Subscribe to the newsletter, and don't miss out.

arrayC++Programming Blogsdata structures

Written by

Anower Hossain
Anower Hossain

This is Anower Hossain. Passionate about programming, and problem-solving.