class Solution {public:    int findRotateSteps(string ring, string key) {        int M = ring.size();        int N = key.size();        auto f = vector
     
      
       >(M,vector
       
        (N + 1,-1));        f[0][0] = 0;                for (int j = 0;j
        
         <= M;k++) {                int index = i + k;                if (index < 0) index += M;                index = index % M;                if (ring[index] == target) {                    if (f[index][j + 1] == -1 || f[index][j + 1] > f[i][j] + 1 + fabs(k) ) {                        f[index][j + 1] = f[i][j] + 1 + fabs(k);                    }                }            }            }        }                int ret = -1;        for (int i = 0;i
         
           f[i][N]) ret = f[i][N];        }        return ret;    }};
         
        
       
      
     

差5分钟，马丹