Find Nth Fibonacci Number using Dynamic Programming (Memoization Approach)

FibonacciDynamicProgramming.cpp

class Solution {
public:
    map<int, int> memory; // for storing precomputed answers.
    
    int fibonacci(int n) {
        if (memory.find(n) != memory.end()) { // if already exists.
            return memory[n]; // just return the precomputed value.
        }
        // Find the n_th Fibonacci number and make a note of it in memory.
        memory[n] = fibonacci(n-1) + fibonacci(n-2);

        return memory[n];
    }
    
    int n_th_fibonacci(int n) {
        memory[1] = 0; // base case that we already know.
        memory[2] = 1; // base case that we already know.
        return fibonacci(n); // find answer.
    }
};