C - Tsundoku, binary search, prefix sums
- problem statements are really simple, like most of AC problems, unlike problem itself.
- we can’t sort as books are stacked given in the question.
- since time to read a book will only accumulate over time.
- therefore constructing a prefix array seems reasonable.
- and then comes the implementing the binary search.
- will traverse over one array, count how many elements present in the second array less then
(k - array_one[i])
- will store in some variable.
Code
```cpp
long long int n, m, k;
cin >> n >> m >> k;
std ::vector arr(n), brr(m);
for (int i = 0; i < n; i++) {
cin >> arr[i];
arr[i] += (i > 0 ? arr[i - 1] : 0);
}
for (int i = 0; i < m; i++) {
cin >> brr[i];
brr[i] += (i > 0 ? brr[i - 1] : 0);
}
long long int ans = 0;
for (int i = 0; i < n; i++) {
if (arr[i] > k)
break;
auto it = upper_bound((brr).begin(), (brr).end(), k - arr[i]);
ans = max(1 + i + (ll)(it - brr.begin()), ans);
}
for (int i = 0; i < m; i++) {
if (brr[i] > k)
break;
auto it = upper_bound((arr).begin(), (arr).end(), k - brr[i]);
ans = max(1 + i + (ll)(it - arr.begin()), ans);
}
cout << ans << '\n';
```
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