HackerEarth Gifts problem solution

YASH PAL, 31 July 202414 February 2026

In this HackerEarth Gifts problem solution This festive Season HackerEarth decided to send gifts to all of its contributors. Xsquare , Sentinel , Subway , darkshadows and Venomous got their favourite gifts i.e ,an array full of integers.

Contrary to that ma5termind got his favourite string str consisting of upper case letters ‘A’ , ‘B’ , ‘C’ , ‘D’ and ‘E’ only. To avoid any kind of comparison ,all the gifts are of same size i.e N. As HackerEarth promotes a very friendly culture, all of them have decided to play together with these gifts. For the purpose to serve …

Xsquare named his array as A.
Sentinel named his array as B.
Subway named his array as C.
Darkshadows named his array as D.
Venomous named his array as E.
They will mainly perform three types of task.

HackerEarth Gifts problem solution

HackerEarth Gifts problem solution.

#include<bits/stdc++.h>
using namespace std;
#define MAX 100002
#define ll long long
#define ft first
#define sd second 
ll A[5][MAX];
ll bit[120][MAX];
map<string , int > M;
int indexx;
void perm(string str,int idx,int n){

    if(idx == n){
        M[str] = indexx;
        indexx++;
        //cout << str << endl;
        return ;
    }
    for(int i=idx;i<n;i++){                     
        int cnt = i-idx;
        int indx = i;
        while(cnt--){
            swap(str[indx],str[indx-1]);
            indx--;
        }           
        perm(str,idx+1,n);
        cnt = i - idx;
        indx = idx;
        while(cnt--){
            swap(str[indx],str[indx+1]);
            indx++;
        }           
    }
}

/*---------bit update ------------------*/
void update(int idx,ll val,int n,int b){

    while(idx<=n){
        bit[b][idx]+=val;
        idx+=(idx&(-idx));
    }
}

ll sum(int idx,int b){
    ll s =0;
    while(idx){
        s+=bit[b][idx];
        idx-=(idx&(-idx));
    }
    return s;
}

ll query(int l,int r,int b){
    return sum(r,b)-sum(l-1,b);
}




int main(){

    int n;
    scanf("%d",&n);
    assert(n>=1&&n<MAX);
    string str;

    for(int i=0;i<5;i++){
        for(int j=1;j<=n;j++){
            scanf("%lld",&A[i][j]);
            assert(A[i][j] <= 1000000000 && A[i][j] >= 1);
        }
    }

    cin >> str;
    assert(str.length() == n);
    for(int i=0;i<n;i++)
        str[i] = tolower(str[i]);
    perm("abcde",0,5);  
    for(map<string,int> :: iterator it= M.begin() ; it!=M.end() ; it++){
        for(int j=0;j<n;j++){
            int indexx = (it->ft)[str[j]-'a']-'a';
            update(j+1,A[indexx][j+1],n,it->sd);        
        }
    }

    int q;
    scanf("%d",&q);
    int queryidx = 0;
    string s="abcde";
    while(q--){
        string type;
        int l,r;
        cin >> type;
        if(type[1]=='c'){   // change 

            char ch;
            cin >> l >> ch;
            ch = tolower(ch);
            str[l-1] = ch; // string update
            l--;
            for(map<string,int> :: iterator it= M.begin() ; it!=M.end() ; it++){
                int indexx = (it->ft)[str[l]-'a']-'a';
                update(l+1,A[indexx][l+1]-query(l+1,l+1,it->sd),n,it->sd);      
            }

        }else if(type[1]=='e'){
            char a,b;
            cin >> a >> b;
            a = tolower(a);
            b = tolower(b);
            swap(s[a-'a'],s[b-'a']);
            queryidx = M[s]; // new index
        }else{
            scanf("%d",&l);
            scanf("%d",&r); 
            assert(l<=r);
            printf("%lldn",query(l,r,queryidx));
        }
    }
    return 0;
}

Second solution

#include <bits/stdc++.h>

using namespace std;

long long A[5][100005];
long long tree[121][100005];

string s;
int n;
map <string, int> m;
map <string, int> :: iterator it;
int cnt;

void update(int tree_idx, int idx, long long val)
{
    while ( idx <= n+1 ) {
        tree[tree_idx][idx] += val;
        idx += (idx & (-idx));
    }
    return;
}

long long query(int tree_idx, int idx)
{
    long long ans = 0;
    while ( idx > 0 ) {
        ans += tree[tree_idx][idx];
        idx -= (idx & (-idx));
    }
    return ans;
}

void pre()
{
    string p = "ABCDE";
    cnt = 1;
    do {
        m[p] = cnt++;
    }
    while ( next_permutation(p.begin(),p.end()) );
    return;
}

int main()
{
    pre();
    int q;
    string str,init="ABCDE";
    cin >> n;
    for ( int i = 0; i < 5; i++ ) {
        for ( int j = 1; j <= n; j++ ) cin >> A[i][j];
    }

    cin >> s;
    s = "X" + s;

    for ( it = m.begin(); it != m.end(); it++ ) {
        int tree_idx = (*it).second;
        string now = (*it).first;
        for ( int i = 1; i <= n; i++ ) update(tree_idx, i, A[now[s[i]-65]-65][i]);
    }

    cin >> q;
    while ( q-- ) {
        cin >> str;
        if ( str == "Qs" ) {
            int a,b;
            cin >> a >> b;
            cout << query(m[init],b) - query(m[init],a-1) << endl;
        }
        else if ( str == "Qe") {
            char a,b;
            cin >> a >> b;
            swap(init[a-65],init[b-65]);
        }
        else {
            int a;
            char b;
            cin >> a >> b;
            for ( it = m.begin(); it != m.end(); it++ ) {
                int tree_idx = (*it).second;
                string now = (*it).first;
                long long val = query(tree_idx, a) - query(tree_idx, a-1);
                update(tree_idx, a, A[now[b-65]-65][a]-val);
            }
        }
    }
    return 0;
}

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