XDOJ_1114_树状数组

Posted 2020-08-17

http://acm.xidian.edu.cn/problem.php?id=1114

 

离线树状数组，线段树也可以。

 

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
using namespace std;

struct arr
{
    int o,x,pos,l,r;
}a[300005];
int tree[300005] = {0},n,m,ans1[100005],ans2[100005];

bool cmp(arr X,arr Y)
{
    if(X.x == Y.x)  return X.o < Y.o;
    return X.x < Y.x;
}

inline int lowbit(int x)
{
    return x & (-x);
}

void update(int pos,int x)
{
    while(pos <= n)
    {
        tree[pos] += x;
        pos += lowbit(pos);
    }
}

int getsum(int pos)
{
    int sum = 0;
    while(pos > 0)
    {
        sum += tree[pos];
        pos -= lowbit(pos);
    }
    return sum;
}

int main()
{
    scanf("%d%d",&n,&m);
    for(int i = 1;i <= n;i++)
    {
        scanf("%d",&a[i].x);
        a[i].pos = i;
        a[i].o = 1;
    }
    int cnt = n;
    for(int i = 1;i <= m;i++)
    {
        scanf("%d%d%d%d",&a[cnt+1].l,&a[cnt+1].r,&a[cnt+1].x,&a[cnt+2].x);
        a[cnt+1].o = 0;
        a[cnt+2].o = 2;
        a[cnt+1].pos = a[cnt+2].pos = i;
        a[cnt+2].l = a[cnt+1].l;
        a[cnt+2].r = a[cnt+1].r;
        cnt += 2;
    }
    sort(a+1,a+1+cnt,cmp);
    for(int i = 1;i <= n;i++)
    {
        if(a[i].o == 1)     update(a[i].pos,1);
        else if(a[i].o == 0)    ans1[i] = getsum(a[i].r)-getsum(a[i].l-1);
        else    ans2[i] = getsum(a[i].r)-getsum(a[i].l-1);
    }
    for(int i = 1;i <= m;i++)   printf("%d\n",ans2[i]-ans1[i]);
    return 0;
}