LeetCode75| 区间集合

目录

[435 无重叠区间](#435 无重叠区间)

[452 用最少的箭引爆气球](#452 用最少的箭引爆气球)

---

435 无重叠区间

class Solution {
public:
    static bool cmp(vector<int>&a,vector<int>&b){
        return a[0] < b[0];
    }
    int eraseOverlapIntervals(vector<vector<int>>& intervals) {
        int res = 0;
        sort(intervals.begin(),intervals.end(),cmp);
        for(int i = 1;i < intervals.size();i++){
            if(intervals[i][0] >= intervals[i - 1][1]){
                intervals[i][1] = max(intervals[i][1],intervals[i - 1][1]);
            }else{
                intervals[i][1] = min(intervals[i][1],intervals[i - 1][1]);
                res++;
            }
        }
        return res;
    }
};

时间复杂度O(nlogn)

空间复杂度O(logn)//排序所需要的栈空间

452 用最少的箭引爆气球

class Solution {
public:
    static bool cmp(vector<int>& a,vector<int>& b){
        return a[0] < b[0];
    }
    int findMinArrowShots(vector<vector<int>>& points) {
        int res = 1;
        sort(points.begin(),points.end(),cmp);    
        for(int i = 1;i < points.size();i++){
            if(points[i][0] <= points[i - 1][1]){
                points[i][1] = min(points[i][1],points[i - 1][1]);
                points[i][0] = max(points[i][0],points[i - 1][0]);
            }else res++; 
        }
        return res;
    }
};

时间复杂度O(nlogn)

空间复杂度O(logn)//排序所需要的栈空间