***Leetcode 632. Smallest Range

https://leetcode.com/problems/smallest-range/description/

 

不错的题 貌似有人头条被问过

class cmp {
  public:
	bool operator()(const pair& n1, const pair& n2) const {
		return n1.first > n2.first;
	}
};

class Solution {
public:
	vector smallestRange(vector >& nums) {
		priority_queue< pair, vector< pair >, cmp > q;
		vector< int > ptrs( nums.size(), 0 );
		vector ret;
		int mx = -1e6;
		
		for (int i = 0; i < nums.size(); i++) {
			q.push( make_pair( nums[i][0], i ) );
			mx = max(mx, nums[i][0]);
        }

		int n = nums.size();
		int ans = mx - q.top().first;
        ret.push_back(q.top().first);
        ret.push_back(mx);
		
		while ( q.size() ) {
			pair tp = q.top();
            // cout << "tp.first" << tp.first << endl;
			q.pop();
            
            if (mx - tp.first < ans) {
                ret[0] = tp.first;
                ret[1] = mx;
                ans = ret[1] - ret[0];
            }
            
            ptrs[ tp.second ] ++;
            if (ptrs[tp.second] >= nums[tp.second].size()) break;
            q.push( make_pair( nums[tp.second][ ptrs[ tp.second ] ], tp.second ) );
            
            mx = max(mx, nums[tp.second][ ptrs[ tp.second ] ]);
				
		}
		
		return ret;
	}
};