Leetcode62. Different paths

Title transmission address : https://leetcode.cn/problems/unique-paths/

Operational efficiency ：

The code is as follows :

  public static int uniquePaths(int m, int n) {
    
        HashMap<String, Integer> map = new HashMap<>();
        int i = uniqPathsWithMap(m, n, map);
        return i;
    }

    public static int uniqPathsWithMap(int m, int n, HashMap<String, Integer> map) {
    
        String key = m + ":" + n;
        // Use map, Improve operational performance 
        if (map.containsKey(key)) {
    
            return map.get(key);
        }
        // Dealing with border situations 
        if (m == 1 || n == 1) {
    
            return 1;
        }
        // If you want to walk to (m,n) coordinates , Yes 2 Maybe , The first is from (m-1,n) To (m,n),  The first 2 One is from (m,n-1) To (m,n)
        int i = uniqPathsWithMap(m - 1, n, map) + uniqPathsWithMap(m, n - 1, map);
        map.put(m + ":" + n, i);
        return i;
    }