Differences between (a+=b)%p; and a =(a+b)%p;

Правка en1, от PUSSY_LICKING_LOLI_69, 2024-08-20 21:59:51

I recently came across this problem while solving E1 of Codeforces Round 967 (Div. 2)

My original code used (a+=b)%p; and it worked perfectly with small test cases, but it gave WA when the test cases get larger. After i changed it to a =(a+b)%p; the code got accepted.

I'm a bit frustrated because it took me until after the contest was finished that i found the dumb mistake that probably stopped me from getting the Candidate Master title, so I made this post to discuss the differences between those 2 syntax to help people avoid the same mistake as me (and mostly just for me to vent T^T )

Here's my original code (Please don't pay attention to the dumb variable names hehe)

My Code

It only worked on test 1, and failed test 2. However, when i changed this line, it worked perfectly

//for(int j = 2;j<=k;j++) (dp2[i][j]+=dp2[i][j-1])%p;
for(int j = 2;j<=k;j++) dp2[i][j]=(dp2[i][j]+dp2[i][j-1])%p;

Can anyone explain why this single line broke my code? :(

История

 
 
 
 
Правки
 
 
  Rev. Язык Кто Когда Δ Комментарий
en1 Английский PUSSY_LICKING_LOLI_69 2024-08-20 21:59:51 3062 Initial revision (published)