DP问题：leetcode(62) Unique Paths

题目：

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.

水题，注意一下边界量的初始

class Solution {
public:
    int uniquePaths(int m, int n) {
        int a[101][101];
        for(int i=1;i<=n;i++) { a[1][i]=1; }
        for(int i=1;i<=m;i++) { a[i][1]=1; }
        for(int i=2;i<=m;i++)
            for(int j=2;j<=n;j++){
                a[i][j]=a[i][j-1]+a[i-1][j];
            }
        return a[m][n];
    }
};