1299. Replace Elements with Greatest Element on Right Side

發表於 | 分類於

problem

solution

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class Solution {
public:
    vector<int> replaceElements(vector<int>& arr) {
        // 從右至左找最大
        int n = arr.size();
        vector<int> ret(n, -1);
        //  17  18  5   4   6   1
        //  18  6   6   6   1   -1
        int mx = arr.back();
        for(int i=n-2;i>-1;--i){
            ret[i] = mx;
            mx = max(mx, arr[i]);
        }
        return ret;
    }
};

analysis

  • time complexity O(n)
  • space complexity O(n)