No.155 - LeetCode? - Remove Covered Intervals

class Solution {
public:
    bool judge(int a,int b,int c,int d){
        if(a <= c && b >= d) return true;
        return false;
    }
    int removeCoveredIntervals(vector<vector<int>>& intervals) {
        int N = intervals.size();
        vector<int> flag(N,0);
        int ans = N;
        for(int i=0;i<N;i++){
            if(flag[i] == 1) continue;
            int a = intervals[i][0];
            int b = intervals[i][1];
            for(int j=0;j<N;j++){
                if( i== j) continue;
                if(flag[j] == 1) continue;
                int c = intervals[j][0];
                int d = intervals[j][1];
                if(judge(a,b,c,d)){
                    ans --;
                    flag[j] = 1;
                }
            }
        }
        return ans;
    }
};