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Practice
Setter:
Tester: Istvan Nagy
Editorialist: Taranpreet Singh
DIFFICULTY
Simple
PREREQUISITES
None
PROBLEM
Given duration of shows of S seasons, each season having an intro song, Determine the time taken to watch all the episodes, while skipping intro song in each episode except once every season.
QUICK EXPLANATION
Simply subtract i-th intro song duration (E_i-1) times, as i-th song would be skipped E_i-1 times. Then take the total of all the episode times.
EXPLANATION
Since this is a simple problem, I’ll explain the solution from two viewpoints for interested readers. It’s perfectly okay to choose any veiwpoint as feels comfortable. Both are essentially same in idea.
Viewpoint 1
In this view point, we would compute the time spent on each episode. We’d subtract the duration of intro song from all except first episode for all seasons. So we have exact times spent on each episodes. We can take total of these and determine total duration.
Viewpoint 2
In this viewpoint, we’d focus on computing the time spent viewing the intro song and time spent viewing content in episodes. Since each intro song is watched exactly once, so sum of duration of each intro song determines the total time spent hearing intro songs.
Computing the time spent viewing content is subtracting the duration of intro song from each episode and adding the remaining episode time.
TIME COMPLEXITY
The time complexity is O(\sum{E_i}) per test case.
The space complexity is O(1) per test case.
SOLUTIONS
Setter's Solution
#include <bits/stdc++.h>
#define pb push_back
#define ll long long int
#define pii pair<int, int>
using namespace std;
FILE *fp;
ofstream outfile;
long long readInt(long long l,long long r,char endd){
long long x=0;
int cnt=0;
int fi=-1;
bool is_neg=false;
while(true){
char g=getchar();
// char g = getc(fp);
if(g=='-'){
assert(fi==-1);
is_neg=true;
continue;
}
if('0'<=g && g<='9'){
x*=10;
x+=g-'0';
if(cnt==0){
fi=g-'0';
}
cnt++;
assert(fi!=0 || cnt==1);
assert(fi!=0 || is_neg==false);
assert(!(cnt>19 || ( cnt==19 && fi>1) ));
} else if(g==endd){
if(is_neg){
x= -x;
}
// cout << x << " " << l << " " << r << endl;
assert(l<=x && x<=r);
return x;
} else {
assert(false);
}
}
}
string readString(int l,int r,char endd){
string ret="";
int cnt=0;
while(true){
char g=getchar();
// char g=getc(fp);
assert(g != -1);
if(g==endd){
break;
}
cnt++;
ret+=g;
}
assert(l<=cnt && cnt<=r);
return ret;
}
long long readIntSp(long long l,long long r){
return readInt(l,r,' ');
}
long long readIntLn(long long l,long long r){
return readInt(l,r,'\n');
}
string readStringLn(int l,int r){
return readString(l,r,'\n');
}
string readStringSp(int l,int r){
return readString(l,r,' ');
}
const int maxt = 5;
const int maxs = 1e5;
const int maxte = 1e5;
const int maxl = 1e5;
int main()
{
int t = readIntLn(1, maxt);
while(t--){
int season = readIntLn(1, maxs);
vector<int> q; q.clear();
for(int i = 0; i < season; i++)q.pb(i == season - 1 ? readIntLn(1, maxl - 1) : readIntSp(1, maxl - 1));
int te = 0;
ll ans = 0;
for(int i = 0; i < season; i++){
int epi = readIntSp(1, maxte);
te += epi;
for(int j = 0; j < epi; j++){
int len = j == epi - 1 ? readIntLn(q[i] + 1, maxl) : readIntSp(q[i] + 1, maxl);
assert(len > q[i]);
if(j == 0)ans += len; else ans += len - q[i];
}
}
assert(te <= maxte);
cout << ans << endl;
}
assert(getchar()==-1);
}
Tester's Solution
#include <iostream>
#include <cassert>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <random>
#include <limits>
#ifdef HOME
#define NOMINMAX
#include <windows.h>
#endif
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define forn(i, n) for (int i = 0; i < (int)(n); ++i)
#define for1(i, n) for (int i = 1; i <= (int)(n); ++i)
#define ford(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define fore(i, a, b) for (int i = (int)(a); i <= (int)(b); ++i)
template<class T> bool umin(T& a, T b) { return a > b ? (a = b, true) : false; }
template<class T> bool umax(T& a, T b) { return a < b ? (a = b, true) : false; }
using namespace std;
long long readInt(long long l, long long r, char endd) {
long long x = 0;
int cnt = 0;
int fi = -1;
bool is_neg = false;
while (true) {
char g = getchar();
if (g == '-') {
assert(fi == -1);
is_neg = true;
continue;
}
if ('0' <= g && g <= '9') {
x *= 10;
x += g - '0';
if (cnt == 0) {
fi = g - '0';
}
cnt++;
assert(fi != 0 || cnt == 1);
assert(fi != 0 || is_neg == false);
assert(!(cnt > 19 || (cnt == 19 && fi > 1)));
}
else if (g == endd) {
assert(cnt > 0);
if (is_neg) {
x = -x;
}
assert(l <= x && x <= r);
return x;
}
else {
//assert(false);
}
}
}
string readString(int l, int r, char endd) {
string ret = "";
int cnt = 0;
while (true) {
char g = getchar();
assert(g != -1);
if (g == endd) {
break;
}
// if(g == '\r')
// continue;
cnt++;
ret += g;
}
assert(l <= cnt && cnt <= r);
return ret;
}
long long readIntSp(long long l, long long r) {
return readInt(l, r, ' ');
}
long long readIntLn(long long l, long long r) {
return readInt(l, r, '\n');
}
string readStringLn(int l, int r) {
return readString(l, r, '\n');
}
string readStringSp(int l, int r) {
return readString(l, r, ' ');
}
int main(int argc, char** argv)
{
#ifdef HOME
if (IsDebuggerPresent())
{
freopen("../COLGLF2_0.in", "rb", stdin);
freopen("../out.txt", "wb", stdout);
}
#endif
int T = readIntLn(1, 5);
forn(tc, T)
{
int S = readIntLn(1, 100'000);
int64_t res = 0;
vector<int> Q(S);
forn(i, S)
{
if (i + 1 == S)
Q[i] = readIntLn(1, 100'000);
else
Q[i] = readIntSp(1, 100'000);
res += Q[i];
}
forn(i, S)
{
int E = readIntSp(1, 100'000);
int EE;
forn(j, E)
{
if (j + 1 == E)
EE = readIntLn(2, 100'000);
else
EE = readIntSp(2, 100'000);
assert(EE > Q[i]);
res += EE - Q[i];
}
}
printf("%lld\n", res);
}
assert(getchar() == -1);
return 0;
}
Editorialist's Solution
import java.util.*;
import java.io.*;
class COLGLF2{
//SOLUTION BEGIN
void pre() throws Exception{}
void solve(int TC) throws Exception{
long time = 0;
int S = ni();
long[] introSong = new long[S];
for(int i = 0; i< S; i++){
introSong[i] = nl();
time += introSong[i];
}
for(int i = 0; i< S; i++){
int E = ni();
for(int j = 0; j< E; j++)time += nl()-introSong[i];
}
pn(time);
}
//SOLUTION END
void hold(boolean b)throws Exception{if(!b)throw new Exception("Hold right there, Sparky!");}
static boolean multipleTC = true;
FastReader in;PrintWriter out;
void run() throws Exception{
in = new FastReader();
out = new PrintWriter(System.out);
//Solution Credits: Taranpreet Singh
int T = (multipleTC)?ni():1;
pre();for(int t = 1; t<= T; t++)solve(t);
out.flush();
out.close();
}
public static void main(String[] args) throws Exception{
new COLGLF2().run();
}
int bit(long n){return (n==0)?0:(1+bit(n&(n-1)));}
void p(Object o){out.print(o);}
void pn(Object o){out.println(o);}
void pni(Object o){out.println(o);out.flush();}
String n()throws Exception{return in.next();}
String nln()throws Exception{return in.nextLine();}
int ni()throws Exception{return Integer.parseInt(in.next());}
long nl()throws Exception{return Long.parseLong(in.next());}
double nd()throws Exception{return Double.parseDouble(in.next());}
class FastReader{
BufferedReader br;
StringTokenizer st;
public FastReader(){
br = new BufferedReader(new InputStreamReader(System.in));
}
public FastReader(String s) throws Exception{
br = new BufferedReader(new FileReader(s));
}
String next() throws Exception{
while (st == null || !st.hasMoreElements()){
try{
st = new StringTokenizer(br.readLine());
}catch (IOException e){
throw new Exception(e.toString());
}
}
return st.nextToken();
}
String nextLine() throws Exception{
String str = "";
try{
str = br.readLine();
}catch (IOException e){
throw new Exception(e.toString());
}
return str;
}
}
}
VIDEO EDITORIAL:
Feel free to share your approach. Suggestions are welcomed as always. 
But in the constraints they said