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Unique Paths

时间:2015-01-19 22:27:00      阅读:150      评论:0      收藏:0      [点我收藏+]

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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?

技术分享

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

Note: m and n will be at most 100.

这是一道非常典型的动态规划的问题

知道递推关系式

paths[i][j] = paths[i - 1][j] + paths[i][j - 1]

注意控制边界条件即可

 1 public class Solution {
 2     public int uniquePaths(int m, int n) {
 3         int paths[][] = new int[m + 1][n + 1];
 4         paths[0][0] = 1;
 5         
 6         for(int i = 1; i < paths.length; i++){
 7             for(int j = 1; j < paths[0].length ; j++){
 8                 if(i == 1|| j == 1)
 9                     paths[i][j] = 1;
10                 if(j != 1 && i != 1)
11                     paths[i][j] = paths[i - 1][j] + paths[i][j - 1];
12             }//for
13         }//for
14         
15         return paths[m][n];
16     }
17 }

 

Unique Paths

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原文地址:http://www.cnblogs.com/luckygxf/p/4234720.html

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