区间合并

vector<pair<int, int>>merge(string s)
{
vector<pair<int, int>>tmp, result;
if (s.empty())
{
return result;
}
int len = s.size(), flag = 1, sum = 0,j=0,left=0,right=0;
while (s[j] == ' '&&j < len - 1)//过滤字符串前面的空格
j++;
for (int i = j; i <= len; i++)//在字符串中提取区间
{
if (s[i] == ' ' || s[i] == '\0')tmp.push_back(make_pair(left, sum)), sum = 0, flag = 1;
else if (s[i] == '-')flag = -1;
else if (s[i] == ',')left = sum, sum = 0, flag = 1;
else sum = flag*(sum * 10 + s[i] - '0');
}
sort(tmp.begin(), tmp.end());//排序
for (int i = 0; i < tmp.size(); i++)//如果第二个区间的前者比第一的后者小，证明可以合并，合并后的区间后者是两个区间后者的大值；反之，则不可以合并
{

if (result.empty())
result.push_back(tmp[i]);
else{
int len = result.size();
right = result[len - 1].second;
if (tmp[i].first <= right)
{
right = (right>tmp[i].second) ? right : tmp[i].second;
result[len - 1].second = right;
}
else
result.push_back(tmp[i]);
}

}
return result;
}