dsa2 min read
Longest Arithmetic Subsequence — DP + Hash Map per Index
Find the longest arithmetic subsequence using dp[i][diff] = length ending at index i with given difference.
Read →
All Posts
1575 articles
dsa2 min read
Count Bad Pairs — Complement Counting with HashMap
Count pairs (i,j) where j-i != nums[j]-nums[i] by counting good pairs via frequency map of nums[i]-i.
Read →
dsa2 min read
Make Sum Divisible by P — Prefix Mod + HashMap
Find the smallest subarray to remove so the remaining sum is divisible by p using prefix modular arithmetic.
Read →
dsa2 min read
Tuple with Same Product — Product Frequency Map
Count tuples (a,b,c,d) where a*b=c*d by counting pairs with each product using a frequency map.
Read →
dsa2 min read
Encode and Decode TinyURL — HashMap Bidirectional Mapping
Design a URL shortener using two hash maps for O(1) encode and decode operations.
Read →
Page 122 of 315