# 1868. Product of Two Run-Length Encoded Arrays
###### tags: `Leetcode` `Medium` `FaceBook`
Link: https://leetcode.com/problems/product-of-two-run-length-encoded-arrays/
## 思路
想法其实不难
用双指针，每次找目前指到的两个array里面最小的frequency，然后把乘积和最小frequency加到ans里面，然后这一个ans里面的两数乘积和上一个ans里面的两数乘积重复，就把上一个改掉
重点是想清楚怎么**优化代码！**
## Code

class Solution {
    public List<List<Integer>> findRLEArray(int[][] encoded1, int[][] encoded2) {
        int idx1 = 0,idx2 = 0;
        List<List<Integer>> ans = new ArrayList<>();
        while(idx1<encoded1.length && idx2<encoded2.length){
            int curr1 = encoded1[idx1][1];
            int curr2 = encoded2[idx2][1];
            int res = encoded1[idx1][0]*encoded2[idx2][0];
            int freq = Math.min(curr1,curr2);
            if(ans.isEmpty() || res!=ans.get(ans.size()-1).get(0)){
                ans.add(Arrays.asList(res, freq));
            }
            else{
                ans.set(ans.size()-1, Arrays.asList(res, freq+ans.get(ans.size()-1).get(1)));
            }
            
            encoded1[idx1][1] -= freq;
            encoded2[idx2][1] -= freq;
            if(encoded1[idx1][1]==0)idx1++;
            if(encoded2[idx2][1]==0)idx2++;
            
        }
        return ans;
    }
}