Sid -> Switching Length

#include <bits/stdc++.h>
using namespace std;

//find the longest switching array.

typedef struct{
    int lengthMaxSwitching;
    int oddElem;
    int evenElem;
} rt;

rt h_solution(vector<int> &A, int index, unordered_map<int, rt> &memo){
    //returns maximum switching array ending at index;
    rt to_return;

    if(memo.count(index)){
        return memo[index];
    }

    if(index == 0){
        to_return.lengthMaxSwitching = 1;
        to_return.oddElem = A[index];
        to_return.evenElem = INT_MAX;
        memo[index] = to_return;
        return to_return;
    }
    if(index == 1){
        to_return.lengthMaxSwitching = 2;
        to_return.oddElem = A[0];
        to_return.evenElem = A[1];
        memo[index] = to_return;
        return to_return;
    }

    rt L = h_solution(A, index-1, memo);
    if(L.lengthMaxSwitching % 2 == 0){
        //i.e current element will be at odd position
        if(A[index]==L.oddElem){
            to_return = L;
            to_return.lengthMaxSwitching+= 1;
            memo[index] = to_return;
            return to_return;
        }
        else{
            to_return.lengthMaxSwitching = 2;
            to_return.evenElem = A[index];
            to_return.oddElem = A[index-1];
            memo[index] = to_return;
            return to_return;
        }
    }
    else{
        //ie current element will be at even position
        if(A[index]==L.evenElem){
            to_return = L;
            to_return.lengthMaxSwitching += 1;
            memo[index] = to_return;
            return to_return;
        }
        else{
            to_return.lengthMaxSwitching = 2;
            to_return.evenElem = A[index];
            to_return.oddElem = A[index-1];
            memo[index] = to_return;
            return to_return;
        }
    }
}

int solution(vector<int> &A){
    if(A.size()<=2) return A.size();

    unordered_map<int, rt> memo;

    int answer = 0;
    for(int i=0; i<A.size(); i++){
        answer = max(answer, h_solution(A, i, memo).lengthMaxSwitching);
    }
    return answer;
}

int main() {
    vector<int> sample = {7,-5, -5, -5, 7, -1, 7};
    cout << solution(sample) << endl;
    return 0;
}