62. Unique Paths

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?

 

 机器人长得真几把欠打

https://blog.csdn.net/zxzxzx0119/article/details/81807910

public class Solution {
    public int uniquePaths(int m, int n) {
        /*
        int[][] ways = new int[m][n];
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (i == 0 || j == 0) ways[i][j] = 1;
                else ways[i][j] = ways[i-1][j] + ways[i][j-1];
            }
        }
        return ways[m-1][n-1];
        */
        int[] dp = new int[n];
        dp[0] = 1;
        for(int i = 0; i < m; i++){
            for(int j = 1; j < n; j++){
                dp[j] += dp[j-1];
            }
        }
        return dp[n-1];
    }
}