LeetCode: Unique Paths 解题报告

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?

public class Solution {
public int uniquePaths(int m, int n) {
if (m <= 0 || n <= 0) {
return 0;
}

int[][] D = new int[m]
;

for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (i == 0 && j == 0) {
D[i][j] = 1;
} else if (i == 0) {
D[i][j] = D[i][j - 1];
} else if (j == 0) {
D[i][j] = D[i - 1][j];
} else {
D[i][j] = D[i - 1][j] + D[i][j - 1];
}
}
}

return D[m  - 1][n - 1];
}
}

View Code