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.
代码语言：txt复制 public int uniquePaths(int m, int n) {
if (m <= 0 || n <= 0) {
return 0;
}
int[][] dp = new int[m][n];
for (int y = 1; y < n; y ) {
dp[0][y] = 1;
}
for (int x = 1; x < m; x ) {
dp[x][0] = 1;
}
for (int y = 1; y < n; y ) {
for (int x = 1; x < m; x ) {
dp[x][y] = dp[x - 1][y] dp[x][y - 1];
}
}
return dp[m - 1][n - 1];
}
