minDistance = function(word1, word2) {

    let dp = new Array(word1.length+1).fill(0).map(item=>{
      return new Array(word2.length+1).fill(0)
    })
    for(let i=1;i<=word1.length;i++){
      dp[i][0] = i
    }
    for(let j=1;j<=word2.length;j++){
      dp[0][j] = j
    }
    // ba
    // ea
  
    for(let i=1;i<=word1.length;i++){
      for(let j=1;j<=word2.length;j++){
        if(word1[i-1]==word2[j-1]){
          dp[i][j] = dp[i-1][j-1]
        }else{
          dp[i][j] = Math.min(
            dp[i][j-1] +1 ,
            dp[i-1][j] +1 ,
            dp[i-1][j-1]+1
          )
        }
      }
    }
    // console.log(dp)
    return dp[word1.length][word2.length]
          

  }
@param {string} word1
@param {string} word2
@return {number}