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题目链接: https://leetcode.com/problems/data-stream-as-disjoint-intervals/
Given a data stream input of non-negative integers a1, a2, ..., an, ..., summarize the numbers seen so far as a list of disjoint intervals.
For example, suppose the integers from the data stream are 1, 3, 7, 2, 6, ..., then the summary will be:
[1, 1] [1, 1], [3, 3] [1, 1], [3, 3], [7, 7] [1, 3], [7, 7] [1, 3], [6, 7]
Follow up:
What if there are lots of merges and the number of disjoint intervals are small compared to the data stream‘s size?
解析：
题目的意思是新加进来的数字如果遇到连续区间就合并
方法一用vector
/** * Definition for an interval. * struct Interval { * int start; * int end; * Interval() : start(0), end(0) {} * Interval(int s, int e) : start(s), end(e) {} * }; */ class SummaryRanges { public: void addNum(int val) { auto Cmp = [](Interval a, Interval b) { return a.start < b.start; }; auto it = lower_bound(vec.begin(), vec.end(), Interval(val, val), Cmp); int start = val, end = val; if(it != vec.begin() && (it-1)->end+1 >= val) it--; while(it != vec.end() && val+1 >= it->start && val-1 <= it->end) { start = min(start, it->start); end = max(end, it->end); it = vec.erase(it); } vec.insert(it,Interval(start, end)); } vector<Interval> getIntervals() { return vec; } private: vector<Interval> vec; }; /** * Your SummaryRanges object will be instantiated and called as such: * SummaryRanges obj = new SummaryRanges(); * obj.addNum(val); * vector<Interval> param_2 = obj.getIntervals(); */
注意：
auto Cmp = [](Interval a, Interval b) { return a.start < b.start; };
这里实际上用的是一个lambda表达式
auto it = lower_bound(vec.begin(), vec.end(), Interval(val, val), Cmp);
这样代码用了C11中的auto，根据初始化的值的类型来推断变量类型的功能，这里it的类型实际上是vector<Interval>::iterator
方法二用set
/** * Definition for an interval. * struct Interval { * int start; * int end; * Interval() : start(0), end(0) {} * Interval(int s, int e) : start(s), end(e) {} * }; */ class SummaryRanges { public: void addNum(int val) { auto Cmp = [](Interval a, Interval b) { return a.start < b.start; }; auto it = lower_bound(vec.begin(), vec.end(), Interval(val, val), Cmp); int start = val, end = val; if(it != vec.begin() && (it-1)->end+1 >= val) it--; while(it != vec.end() && val+1 >= it->start && val-1 <= it->end) { start = min(start, it->start); end = max(end, it->end); it = vec.erase(it); } vec.insert(it,Interval(start, end)); } vector<Interval> getIntervals() { return vec; } private: vector<Interval> vec; }; /** * Your SummaryRanges object will be instantiated and called as such: * SummaryRanges obj = new SummaryRanges(); * obj.addNum(val); * vector<Interval> param_2 = obj.getIntervals(); */
352. Data Stream as Disjoint Intervals
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原文地址：http://www.cnblogs.com/raichen/p/5605472.html
