LeetCode 62 Unique Paths

LeetCode 62 Unique Paths

题目链接：https://leetcode.com/problems/unique-paths/description/

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?

一道简单的动态规划题，依旧找状态方程和边界情况，到达（i,j)的路径数目、count[i][j]=count[i-1][j]+count[i][j-1],边界情况：在第一行和第一列，路径数目都是1.

public int uniquePaths(int m, int n) {
int count[][]=new int [m]
;
count[0][0]=1;
int i,j;
for(i=1;i<m;i++){   //第一列
count[i][0]=1;
}
for(j=1;j<n;j++){   //第一行
count[0][j]=1;
}
for(i=1;i<m;i++){
for(j=1;j<n;j++){
count[i][j]=count[i-1][j]+count[i][j-1];
}
}
return count[m-1][n-1];
}