## LeetCode: Unique Paths 解题报告

A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).

The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).

How many possible unique paths are there?

Above is a 3 x 7 grid. How many possible unique paths are there?

Note: m and n will be at most 100.

SOLUTION 1:

 1 public class Solution {
2     public int uniquePaths(int m, int n) {
3         if (m <= 0 || n <= 0) {
4             return 0;
5         }
6
7         int[][] D = new int[m][n];
8
9         for (int i = 0; i < m; i++) {
10             for (int j = 0; j < n; j++) {
11                 if (i == 0 && j == 0) {
12                     D[i][j] = 1;
13                 } else if (i == 0) {
14                     D[i][j] = D[i][j - 1];
15                 } else if (j == 0) {
16                     D[i][j] = D[i - 1][j];
17                 } else {
18                     D[i][j] = D[i - 1][j] + D[i][j - 1];
19                 }
20             }
21         }
22
23         return D[m  - 1][n - 1];
24     }
25 }
View Code

posted on 2015-04-08 02:38  Yu's Garden  阅读(710)  评论(0编辑  收藏