• If you don't wash any dish, then your final score will be . Let's call that x.
• Now, suppose you wash some dishes. Each dish i that you wash will contribute with p_i to the answer instead of  - d_i, so for all the dishes that you wash, you must add p_i + d_i to x.
• Naturally, we want to take the elements with biggest p_i + d_i, so we sort the dishes in non-increasing order of p_i + d_i and then our answer will be .-

In this problem we are affected by a total amount of (p[i]+d[i]) so lets create another variable x =p[i]+d[i] and now sort the structure first with respect to x and if x is equal then with respect to p[i]. This would be an optimal approach because we'll be taking the values that would affect our total payment to a maximum extent. My code :https://ideone.com/dvm2ah

in the name of allah, most mrcifull

consider this test case:

2 1

1000 9

999 1

if we sort in non-increasing order of pi — di we will chose second one for washing and we will have 9 — 999 money

but if we sort in non-increasing order of pi + di we will chose first one and we will have 1000 — 1 money

i wanna say thank you spontaneously for this blog.