代码随想录31|452. 用最少数量的箭引爆气球，435. 无重叠区间，763.划分字母区间

452. 用最少数量的箭引爆气球

链接地址

class Solution {
private:
    static bool cmp(const vector<int>& a, const vector<int>& b) {
        return a[0] < b[0];//从小到大排序
    }
public:
    int findMinArrowShots(vector<vector<int>>& points) {
        if (points.size() == 0) return 0;
        sort(points.begin(), points.end(), cmp);
        int result = 1;
        for (int i = 1; i < points.size(); i++) {
            if (points[i - 1][1] < points[i][0]) {
                result++;
            } else {
                points[i][1] = min(points[i - 1][1], points[i][1]);//更新point[i]
            }
        }
        return result;
    }
};

435. 无重叠区间

链接地址

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

763.划分字母区间

链接地址

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