HDU 2689 Sort it

Tree_array;

The portal:http://acm.hdu.edu.cn/showproblem.php?pid=2689

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <algorithm>

using namespace std;

const int  M = 20005;

int  Bit[M+5];

void Insert(int  x,int  value) {
	for(int  i = x ; i <= M ; i += i & -i) {
		Bit[i] += value;
	}
}

int  Query(int  x) {
	int  ret = 0;
	for(int  i = x ; i ; i -= i & -i) {
		ret += Bit[i];
	}
	return ret;
}

void Deal_with() {
	int n;
	while(~scanf("%d",&n)) {
		memset(Bit,0,sizeof(Bit));
		int tempa;
		int cnt = 0;
		for(int i = 0 ; i < n ; i++) {
			scanf("%d",&tempa);
			cnt += i - Query(tempa);
			Insert(tempa,1);
		}
		printf("%d\n",cnt);
	}
}

int main(void) {
	//freopen("a.in","r",stdin);
	Deal_with();
	return 0;
}