poj3067 Japan

标签：树状数组

Description

Input

Output

Sample Input

1
3 4 4
1 4
2 3
3 2
3 1

Sample Output

Test case 1: 5

这题和star,cows差不多，把读入的坐标看做x,y，那么先按x进行升序排序，如果x相同的话就按照y升序排序。然后依次循环，加上比a[i].y大的线段的个数。注意用__int64

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<vector>
#include<map>
#include<queue>
#include<stack>
#include<string>
#include<algorithm>
using namespace std;
#define maxn 3005
int b[maxn];
struct node{
	int x,y;
}a[maxn*maxn];

bool cmp(node a,node b){
	if(a.x==b.x)return a.y<b.y;
	return a.x<b.x;
}

int lowbit(int x){
	return x&(-x);
}
void update(int pos,int num)
{
	while(pos<=maxn){
		b[pos]+=num;pos+=lowbit(pos);
	}
}
int getsum(int pos)
{
	int num=0;
	while(pos>0){
		num+=b[pos];pos-=lowbit(pos);
	}
	return num;
}

int main()
{
	int n,m,i,j,T,k,num1=0;
	__int64 sum;
	scanf("%d",&T);
	while(T--)
	{
		scanf("%d%d%d",&n,&m,&k);
		for(i=1;i<=k;i++){
			scanf("%d%d",&a[i].x,&a[i].y);
			a[i].x++;a[i].y++;
		}
		sort(a+1,a+1+k,cmp);
		memset(b,0,sizeof(b));
		sum=0;
		for(i=1;i<=k;i++){
			sum+=i-1-getsum(a[i].y);
			update(a[i].y,1);
		}
		num1++;
		printf("Test case %d: %I64d\n",num1,sum);
	}
	return 0;
}

poj3067 Japan

标签：树状数组

原文地址：http://blog.csdn.net/kirito_acmer/article/details/46350723