HDU 4217 Data Structure?（树状数组） - c++编程基础

Problem Description Data structure is one of the basic skills for Computer Science students, which is a particular way of storing and organizing data in a computer so that it can be used efficiently. Today let me introduce a data-structure-like problem for you.
Original, there are N numbers, namely 1, 2, 3...N. Each round, iSea find out the Ki-th smallest number and take it away, your task is reporting him the total sum of the numbers he has taken away.

Input The first line contains a single integer T, indicating the number of test cases.
Each test case includes two integers N, K, K indicates the round numbers. Then a line with K numbers following, indicating in i (1-based) round, iSea take away the Ki-th smallest away.

Technical Specification
1. 1 <= T <= 128
2. 1 <= K <= N <= 262 144
3. 1 <= Ki <= N - i + 1

Output For each test case, output the case number first, then the sum.
Sample Input

Sample Output

Case 1: 3
Case 2: 14

题意：n个数1-n，k次操作，每次取出第ki小的数。问所有取出数字之和。

思路：树状数组。开始所有位置都是1，如果有数字被去掉就-1。然后在查找第ki小的数字的时候，利用树状数组去进行求和，看数字个数为k时是第几个。

代码：

#include 
  
   
#include 
   
     #include 
    
      using namespace std; const int N = 277777; int t, n, m, bit[N], num, i; long long ans; void add(int x, int v) { while (x <= n) { bit[x] += v; x += (x&(-x)); } } int Sum(int k) { int num = 0; int x = 0; for (int i = 18; i >= 0; i--) { if (x + (1<