[303] 区域和检索 - 数组不可变

class NumArray {
public:
    vector<int> n;
    NumArray(vector<int>& nums) {
        int res = 0;
        // n.resize(nums.size());
        n.push_back(res);
        for(int i = 0; i<nums.size() ;i++){
            // nums[i] += nums[i-1];
            res += nums[i];
            cout<<res<<endl;
            n.push_back(res);
        }
    }
    int sumRange(int i, int j) {
        cout<<n[j+1] <<" "<<n[i]<<endl;
        return n[j+1] - n[i];
    }
};