Shave Beaver! CodeForces - 331B2 (线段树)

题面

The Smart Beaver has recently designed and built an innovative nanotechnologic all-purpose beaver mass shaving machine, "Beavershave 5000". Beavershave 5000 can shave beavers by families! How does it work? Very easily!

题意

在一个数组里面,取出值从a到b的序列,但是每次取出数的必须是连续的.

求每次最少取多少次.

询问中存在交换操作

思路

线段数维护区间和.

点\(x\)表示\(x+1\)是否在\(x\)后面.

#include<iostream>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<ctime>

#define fuck(x) cerr<<#x<<" = "<<x<<endl;
#define debug(a, x) cerr<<#a<<"["<<x<<"] = "<<a[x]<<endl;
#define lson l,mid,ls
#define rson mid+1,r,rs
#define ls (rt<<1)
#define rs ((rt<<1)|1)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
const int loveisblue = 486;
const int maxn = 300086;
const int maxm = 100086;
const int inf = 0x3f3f3f3f;
const ll Inf = 999999999999999999;
const int mod = 1000000007;
const double eps = 1e-6;
const double pi = acos(-1);

int num[maxn], pos[maxn];

int bit[maxn];

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

int query(int pos) {
    int ans = 0;
    while (pos) {
        ans += bit[pos];
        pos -= lowbit(pos);
    }
    return ans;
}

void update(int pos, int val) {
    while (pos < maxn) {
        bit[pos] += val;
        pos += lowbit(pos);
    }
}

int main() {
    ios::sync_with_stdio(true);
#ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
#endif

    int n;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) {
        scanf("%d", &num[i]);
        pos[num[i]] = i;
    }

    for (int i = 1; i < n; i++) {
        if (pos[i] > pos[i + 1]) {
            update(i, 1);
        }
    }
    int m;
    scanf("%d", &m);
    while (m--) {
        int type;
        scanf("%d", &type);
        if (type == 1) {
            int l, r;
            scanf("%d%d", &l, &r);
            printf("%d\n", query(r-1) - query(l - 1) + 1);
        } else {
            int x,y;
            scanf("%d%d",&x,&y);
            swap(num[x],num[y]);
            x=num[x];
            y=num[y];
            int t1 = pos[x];
            int t2 = pos[y];
            if(t1>t2){
                swap(x,y);
                swap(t1,t2);
            }
            if(pos[x+1]>=pos[x]&&pos[x+1]<=pos[y]){
                update(x,1);
            }if(x>1&&x-1!=y&&pos[x-1]>=pos[x]&&pos[x-1]<=pos[y]){
                update(x-1,-1);
            }
            if(pos[y+1]>=pos[x]&&pos[y+1]<=pos[y]){
                update(y,-1);
            }if(y>1&&y-1!=x&&pos[y-1]>=pos[x]&&pos[y-1]<=pos[y]){
                update(y-1,1);
            }
            swap(pos[x],pos[y]);
        }
    }
    return 0;
}