Max Increase to Keep City Skyline

给一个2d数组, 求不改变里面数字对应行列最大值的情况下, 数组数字最大增加多少.

这题读懂题很关键, 先找行列对应的最大值, 然后再用两个值中小的那个减去现有的值, res += min(row[i], col[j]) – grid[i][j], where row[i], col[j] is the max number of i, j.

class Solution {
public:
    int maxIncreaseKeepingSkyline(vector<vector<int>>& grid) {
        int n = grid.size();
        int m = grid[0].size();
        vector<int> col(m);
        vector<int> row(n);
        for(int i = 0; i < n; i++) {
            for(int j = 0; j < m; j++) {
                row[i] = max(row[i], grid[i][j]);
                col[j] = max(col[j], grid[i][j]);
            }
        }
        int res = 0;
        for(int i = 0; i < n; i++) {
            for(int j = 0; j < m; j++) {
                res += min(row[i], col[j]) - grid[i][j];
            }
        }
        return res;
    }
};