Description
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.
Note: You can only move either down or right at any point in time.
Solution
DP
class Solution {
public int minPathSum(int[][] grid) {
if (grid == null || grid.length == 0 || grid[0].length == 0) {
return 0;
}
int m = grid.length;
int n = grid[0].length;
int[][] minPathSum = new int[m][n];
for (int i = 0; i < m; ++i) {
for (int j = 0; j < n; ++j) {
minPathSum[i][j] = grid[i][j];
if (i > 0 && j > 0) {
minPathSum[i][j] += Math.min(minPathSum[i - 1][j], minPathSum[i][j - 1]);
} else if (i > 0) {
minPathSum[i][j] += minPathSum[i - 1][j];
} else if (j > 0) {
minPathSum[i][j] += minPathSum[i][j - 1];
}
}
}
return minPathSum[m - 1][n - 1];
}
}
