for (int k=i;k<=i+len;k++)
if (dp[i][k]+dp[k+1][i+len]+s(i,i+len)<=dp[i][i+len])
dp[i][i+len]=dp[i][k]+dp[k+1][i+len]+s(i,i+len),r[i][i+len]=k;
如果把小于等于改成小于就wa