没有网址qwq

没有oj

翻树状数组看到求逆序对先复习一下归并求逆序对qwq

逆序对真是个神奇的东西啊QAQ

纯属随手一打随手一贴quq

1 #include
     
       2 #include
      
        3 using namespace std; 4 int n, a[100010], b[100010], cnt = 0; 5 void merge_sort(int l, int r) { 6     if(r-l > 0) {//if 打成 while 7         int mid = (l+r)/2; // int mid = (l+r)>>1  写成 >>2 ???? 8         int i = l, p = l, q = mid+1; 9         merge_sort(l, mid);10         merge_sort(mid+1, r);11         while(p <= mid || q <= r) {12             if(q > r || ((p<=mid) && a[p] <= a[q])) //p<=mid !!!!!别打成p
       
         0) 外20     }21 }22 int main() {23     scanf("%d", &n);24     for(int i = 1; i <= n; i++) {25         scanf("%d", &a[i]);26     }27     merge_sort(1, n);28     printf("qwq排序后：\n");29     for(int i = 1; i <= n; i++) 30         cout<
        
         <<' ';31     cout<
         
          <<"quq逆序对数："<
          
           <
          
         
        
       
      
     

 一个merge_sort 你能错出这么多花样？？