插入排序

描述：遍历向量，为每个元素找到它应该在的位置，插入。

template <typename T>
void insertionSort(vector<T>& v)
{
   int i, j, n = v.size();
   T target;

 // place v[i] into the sublist
 //   v[0] ... v[i-1], 1 <= i < n,
 // so it is in the correct position
   for (i = 1; i < n; i++)
   {
      // index j scans down list from v[i] looking for
      // correct position to locate target. assigns it to
      // v[j]
      j = i;
      target = v[i];
      // locate insertion point by scanning downward as long
      // as target < v[j-1] and we have not encountered the
      // beginning of the list
      while (j > 0 && target < v[j-1])//定位插入点
      {
         // shift elements up list to make room for insertion
         v[j] = v[j-1];
         j--;
      }
      // the location is found; insert target
      v[j] = target;　　　　　　　　//插入
   }
}