Leetcode|Medium|Interval Greedy|56. Merge Interval

1 Greedy algorithm traverses once

• Merge if overlap
• Add if not overlapping

class Solution {
    
    
public:
    static bool cmp(const vector<int>& a, const vector<int>& b) {
    
    
        return a[0] < b[0];
    }
    vector<vector<int>> merge(vector<vector<int>>& intervals) {
    
    
        if (intervals.empty()) return {
    
    };
        // 起始点靠前的优先排列
        sort(intervals.begin(), intervals.end(), cmp);
        vector<vector<int>> solution;
        solution.emplace_back(intervals[0]);
        for (int i = 1; i < intervals.size(); i++) {
    
    
            // 1.重叠则合并
            if (intervals[i][0] <= solution.back()[1]) 
                solution.back()[1] = max(solution.back()[1], intervals[i][1]);
            // 2.不重叠则添加
            else solution.emplace_back(intervals[i]);
        }
        return solution;
    }
};

Thanks

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