src/main/java/com/fishercoder/solutions/_64.java

package com.fishercoder.solutions;

public class _64 {
    public static class Solution1 {
        /**
         * Same idea as _70: have to initialize the first row and the first column and start the for
         * loop from i==1 and j==1 for the rest of the matrix.
         */
        public int minPathSum(int[][] grid) {
            if (grid == null || grid.length == 0) {
                return 0;
            }

            int height = grid.length;
            int width = grid[0].length;
            int[][] dp = new int[height][width];
            dp[0][0] = grid[0][0];
            for (int i = 1; i < height; i++) {
                dp[i][0] = dp[i - 1][0] + grid[i][0];
            }
            for (int j = 1; j < width; j++) {
                dp[0][j] = dp[0][j - 1] + grid[0][j];
            }
            for (int i = 1; i < height; i++) {
                for (int j = 1; j < width; j++) {
                    dp[i][j] = Math.min(dp[i - 1][j], dp[i][j - 1]) + grid[i][j];
                }
            }
            return dp[height - 1][width - 1];
        }
    }
}