1、QList常用操作（查找、插入、排序）

（1）QList查找（前提：已排序）

/*[查找val在列表（已排序）中的位置，返回值范围[-1,0,,size()-1]]*/
int posOf(const QList<int> &list1, int val)
{auto it = std::find_if(list1.begin(), list1.end(), [val](int itemVal) {return (itemVal == val);});return ((it != list1.end()) ? (it - list1.begin()) : -1);
}

示例：list = 5,7,11,13,17,19
Pos of 3 is [-1], 11 is [2], 19 is [5], 23 is [-1].

（2）QList插入（前提：已排序）

/*[获取val在列表（已排序）中的插入位置，返回值范围为[0,,size()]]*/
int insertPosOf(const QList<int> &list1, int val)
{auto it = std::lower_bound(list1.begin(), list1.end(), val, [](int itemVal, int val) {return itemVal < val;});return (it - list1.begin());
}

示例：list = 5,7,11,13,17,19
Insert pos of 3 is [0], 11 is [2], 19 is [5], 23 is [6].

(3) QList排序

• 升序

QList<int> list;
……
std::sort(list.begin(), list.end(), std::less<int>{});

或

std::sort(list.begin(), list.end());

示例：list << 37 << 23 << 83 << 71 << 91 << 53 << 11 << 61 << 19;
list ASC = 11,19,23,37,53,61,71,83,91

• 降序

std::sort(list.begin(), list.end(), std::greater<int>{});

示例：list << 37 << 23 << 83 << 71 << 91 << 53 << 11 << 61 << 19;
list DESC = 91,83,71,61,53,37,23,19,11

2、QSet常用操作（交集）

QList<int> listL;
QList<int> listR;
QList<int> list1;
……
{QSet<int> set1 = QSet(list1.constBegin(), list1.constEnd());QSet<int> setL = QSet(listL.cbegin(), listL.cend());set1.intersect(setL);QList<int> list1L = QList(set1.cbegin(), set1.cend());std::sort(list1L.begin(), list1L.end());
}

示例：
listL << 0 << 2 << 4 << 6 << 8 << 10 << 12 << 14 << 16 << 18 << 20 << 22;
listR << 1 << 3 << 5 << 7 << 9 << 11 << 13 << 15 << 17 << 19 << 21 << 23;
list1 << 3 << 6 << 8 << 11 << 14 << 15 << 18 << 21;

list1L(list1 intersect listL) = 6,8,14,18
list1R(list1 intersect listR) = 3,11,15,21