@xixi003

Leetcode-Unique Paths


题目描述

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?

Note: m and n will be at most 100.

AC代码

#include <iostream>
#include <cstdio>
#include <vector>

using namespace std;

int uniquePaths(int m, int n)
{
    	vector<int> f(n, 0);
    	f[0] = 1;
    	for(int i = 0; i < m; i++)
    	{
    		for(int j = 1; j < n; j++)
    		{
    			//初始状体f[i][j], (1,1)->(i,j),f[i][j] = f[i-1][j] + f[i][j-1]
    			f[j] = f[j - 1] + f[j];
    		}
    	}
    	return f[n - 1];
}

int main()
{
    	int m, n;
    
    #ifndef ok
    	freopen("in3.in", "r", stdin);
    	freopen("std3.out", "w", stdout);
    #endif
    
    	while(cin>>m>>n)
    		cout<<uniquePaths(m,n)<<endl;
    
    #ifndef ok
    	fclose(stdin);
    	fclose(stdout);
    #endif
    
    	return 0;
}