279. Perfect Squares

class Solution {
public:
    int numSquares(int n) {
        vector<int> res(n + 1, 5);
        res[0] = 0;
        for (int i = 1; i <= n; i++)
            for (int j = 1; j * j <= i; j++)
                res[i] = min(res[i - j * j] + 1, res[i]);
        return res[n];

//bfs just died when submitting anwser
/*        vector<int> res(n + 1, -1);
        vector<int> squareNumber;
        queue<int> BFS;
        for (int i = 1; i * i <= n; i++) {
            squareNumber.push_back(i * i);
            BFS.push(i * i);
            res[i * i] = 1;
        }

        if (squareNumber.empty() || squareNumber.back() == n) return 1;
        while (!squareNumber.empty()) {
            int curr = BFS.front() ;
            for (int i = 0; i < squareNumber.size(), curr + squareNumber[i] <= n; i++) {
                if (curr + squareNumber[i] == n) return res[curr] + 1;
                if (res[curr + squareNumber[i]] == -1) {
                    BFS.push(curr + squareNumber[i]);
                    res[curr + squareNumber[i]] = res[curr] + 1;
                    cout<<curr + squareNumber[i]<<' '<<res[curr + squareNumber[i]]<<endl;
                }
            }
            BFS.pop();
        }

        return res[n];*/
    }
};