lintcode-easy-Minimum Path Sum

Posted 2020-06-17 哥布林工程师

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path.

 

动态规划，比较直接，不多说了

public class Solution {
    /**
     * @param grid: a list of lists of integers.
     * @return: An integer, minimizes the sum of all numbers along its path
     */
    public int minPathSum(int[][] grid) {
        // write your code here
        if(grid == null || grid.length == 0 || grid[0] == null || grid[0].length == 0)
            return 0;
        
        int m = grid.length;
        int n = grid[0].length;
        int[][] result = new int[m][n];
        result[0][0] = grid[0][0];
        
        for(int i = 1; i < n; i++)
            result[0][i] = result[0][i - 1] + grid[0][i];
        for(int i = 1; i < m; i++)
            result[i][0] = result[i - 1][0] + grid[i][0];
        
        for(int i = 1; i < m; i++){
            for(int j = 1; j < n; j++){
                result[i][j] = grid[i][j] + Math.min(result[i - 1][j], result[i][j - 1]);
            }
        }
        
        return result[m - 1][n - 1];
    }
}