leetcode@ [303/304] Range Sum Query - Immutable / Range Sum Query 2D - Immutable

https://leetcode.com/problems/range-sum-query-immutable/

class NumArray {

public: vector<int> vec;
public:
    NumArray(vector<int> &nums) {
        if(nums.empty()) return;
        else {
            vec.push_back(nums[]);
            for(int i=;i<nums.size();++i) vec.push_back(vec[i-] + nums[i]);
        }
    }

    int sumRange(int i, int j) {
        if(i< || j>=vec.size()) return ;
        if(i==) return vec[j];
        else return vec[j] - vec[i-];
    }
};

// Your NumArray object will be instantiated and called as such:
// NumArray numArray(nums);
// numArray.sumRange(0, 1);
// numArray.sumRange(1, 2);

https://leetcode.com/problems/range-sum-query-2d-immutable/

class NumMatrix {
public:
    vector<vector<int>> vec;
    NumMatrix(vector<vector<int>> &matrix) {
        if(matrix.size() ==  || matrix[].size() == ) return;
        vec.resize(matrix.size());
        for(int i=;i<vec.size();++i) vec[i].resize(matrix[].size());

        vec[][] = matrix[][];
        for(int col=;col<vec[].size();++col) vec[][col] = matrix[][col] + vec[][col-];

        for(int row=;row<vec.size();++row) {
            for(int col=;col<vec[row].size();++col) {
                if(col == ) vec[row][col] = matrix[row][col];
                else vec[row][col] = matrix[row][col] + vec[row][col-];
            }
        }

        for(int row=;row<vec.size();++row) {
            for(int col=;col<vec[row].size();++col) {
                vec[row][col] += vec[row-][col];
            }
        }

        for(int i=;i<vec.size();++i) {
            for(int j=;j<vec[i].size();++j) cout<<vec[i][j]<<" ";
            cout<<endl;
        }
    }
    int sumRegion(int row1, int col1, int row2, int col2) {
        if(row1< || row2>=vec.size() || col1< || col2>=vec[].size()) return ;

        int leftTop = ;
        if(row1 ==  || col1 == ) leftTop = ;
        else if(row1 && col1) leftTop = vec[row1-][col1-];

        int ret1 = ;
        if(row1 == ) ret1 = vec[row2][col2];
        else if(row1 > ) ret1 = vec[row2][col2] - vec[row1-][col2];

        int ret2 = ;
        if(col1 == ) ret2 = ret1;
        else if(col1 > ) ret2 = ret1 - vec[row2][col1-] + leftTop;

        return ret2;
    }
};

// Your NumMatrix object will be instantiated and called as such:
// NumMatrix numMatrix(matrix);
// numMatrix.sumRegion(0, 1, 2, 3);
// numMatrix.sumRegion(1, 2, 3, 4);