1124

class Solution {
public:
    int longestWPI(vector<int>& hours) {
        int curr=0, ans=0;
        unordered_map<int, int> seen;
        for(int i=0; i<hours.size(); i++){
            curr += ((hours[i]>8) ? 1:-1);
            if(curr > 0)
                ans = i+1;
            if(seen.find(curr) == seen.end()){
                seen[curr] = i;
            }
            if(seen.find(curr-1) != seen.end()){
                ans = max(ans, i-seen[curr-1]);
            }
        }
        return ans;
    }
};