Re: [閒聊] 每日leetcode

[dont (dont)]

3160. Find the Number of Distinct Colors Among the Balls

## 思路

兩個hash map
一個紀錄球的顏色, 一個紀錄每種顏色的個數

每次QUERY更新兩個map
如果球顏色改變, 就減掉原本顏色個數


## Code

```cpp
class Solution {
public:
    vector<int> queryResults(int limit, vector<vector<int>>& queries) {
        unordered_map<int, int> balls;
        unordered_map<int, int> counter;

        vector<int> res;
        for (auto& query: queries) {
            int b=query[0], c=query[1];
            if (balls.find(b) != balls.end()) {
                if (--counter[balls[b]] == 0) {
                    counter.erase(balls[b]);
                }
            }
            balls[b] = c;
            counter[c]++;
            res.push_back(counter.size());
        }
        return res;
    }
};
```

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