slinding window 可以逐漸取得正確的涵蓋範圍，先用right開始從頭加，加到超過target就開始用left從頭減。

class Solution {
public:
    int minOperations(vector<int>& nums, int x) {
        int target = 0;
        for(int num : nums){
            target += num;
        }
        target -= x;
        if(target == 0){
            return nums.size();
        }

        int cur = 0;
        int l = 0;
        int max_len = 0;
        for(int r = 0; r < nums.size(); r++){
            cur += nums[r];
            while(cur > target && l <= r){
                cur -= nums[l];
                l++;
            }
            if(cur == target){
                max_len = max(max_len, r - l + 1);
            }
        }
        return max_len ? nums.size() - max_len : -1;
    }
};