不同路径的数目

import java.util.*;

 

public class Solution {

/**

*

* @param m int整型

* @param n int整型

* @return int整型

*/

public int uniquePaths (int m, int n) {

if (m == 1 || n == 1) {

return 1;

}

int [][] arr = new int[m][n];

for (int i = 0; i < m; i++) {

arr[i][0] = 1;

}

for (int i = 0; i < n; i++) {

arr[0][i] = 1;

}

for (int i = 1; i < m; i++) {

for (int j = 1; j < n; j++) {

arr[i][j] = arr[i - 1][j] + arr[i][j - 1];

}

}

return arr[m - 1][n - 1];

 

}

}