Please help getting wrong answer exchanging coins

#1
#2

Hey! you checking for n if it is divisible by 2, 3 or 4 is wrong. Its nowhere mentioned in the problem statement that the number n must be divisible by 2, 3 or 4. For example you have 1 coin with N = 5. You’ll recieve 3 coins with numbers 2, 1 and 1 respectively. Remove the check of number N and see if this resolves your problem.

    ll a, b, c;
    a = ec(n / 2, dp);
    b = ec(n / 3, dp);
    c = ec(n / 4, dp);
    dp[n] = max(n, a + b + c);
#3

Also you must pass the dp (unordered_map) by reference or declare it globally otherwise you’ll get TLE as the unordered_map will pass by copy.

ll ec(ll n, unordered_map<ll, ll> &dp) {

or declare it globally like this :point_down:

#4

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