64 Minimum Path Sum

public class Solution {
    public int minPathSum(int[][] grid) {
        if (grid == null || grid.length == 0) {
            return 0;
        }
        int[][] min = new int[grid.length][grid[0].length];
        min[0][0] = grid[0][0];
        
        for (int i = 1; i< grid.length; i++) {
            min[i][0] = min[i - 1][0] + grid[i][0];
        }
        for (int j = 1; j < grid[0].length; j++) {
            min[0][j] = min[0][j - 1] + grid[0][j];
        }
        
        for (int i = 1; i< grid.length; i++) {
            for (int j = 1; j < grid[0].length; j++) {
                min[i][j] = Math.min(min[i -1][j], min[i][j - 1]) + grid[i][j];
            }
        }
        return min[grid.length -1][grid[0].length - 1];
    }
}

DP

min[i][j]= Math.min(min[i-1][j], min[i][j -1]) + grid[i][j]