codeforces895E. Eyes Closed

题目链接

codeforces895E. Eyes Closed

题解

线段树维护期望和

写出修改两区间的相互影响

就是一个区间修改

emmm考试的代码过不去，这么松的spj都过不去Orz，每次和答案差0.001*ans左右...

可能是我每次直接对区间暴力统计右区间的影响，然后直接打个修改区间tag....

求解

代码

std:

#include <iostream>
#include <cstring>
#include <cmath>
#include <cstdio>
#include <algorithm>
#include <queue>
#include <vector>
#include <map>
#include <complex>

#define inf 0x3f3f3f3f
#define eps 1e-10

#define lc k << 1
#define rc k << 1 | 1

using namespace std;

typedef long long ll;
typedef pair<ll, int> P;
ll p;
double tmp[200005];

struct node{
    double dat, tag1, tag2;
    int l, r;
};
struct seg{
    node d[800005];

    void pushup(int k){
        d[k].dat = d[lc].dat + d[rc].dat;
    }

    void build(int k, int l, int r){
        d[k].l = l; d[k].r = r; d[k].tag1 = 0; d[k].tag2 = 1;
        if(l == r){
            d[k].dat = tmp[l];
            return;
        }
        int mid = (l + r) >> 1;
        build(lc, l, mid);
        build(rc, mid + 1, r);
        pushup(k);
    }

    void add(int k, double x){
        double len = d[k].r - d[k].l + 1;
        d[k].dat = (d[k].dat + x * len);
        d[k].tag1 = (d[k].tag1 + x);
    }

    void mul(int k, double x){
        d[k].dat = d[k].dat * x;
        d[k].tag1 = d[k].tag1 * x;
        d[k].tag2 = d[k].tag2 * x;
    }

    void pushdown(int k){
        if(fabs(d[k].tag2 - 1) > eps){
            mul(lc, d[k].tag2);
            mul(rc, d[k].tag2);
            d[k].tag2 = 1;
        }
        if(fabs(d[k].tag1) > eps){
            add(lc, d[k].tag1);
            add(rc, d[k].tag1);
            d[k].tag1 = 0;
        }
    }

    void add(int k, int l, int r, double x){
        if(l <= d[k].l && d[k].r <= r){
            add(k, x); return;
        }
        pushdown(k);
        int mid = (d[k].l + d[k].r) >> 1;
        if(l <= mid) add(lc, l, r, x);
        if(r > mid) add(rc, l, r, x);
        pushup(k);
    }

    void mul(int k, int l, int r, double x){
        if(l <= d[k].l && d[k].r <= r){
            mul(k, x); return;
        }
        pushdown(k);
        int mid = (d[k].l + d[k].r) >> 1;
        if(l <= mid) mul(lc, l, r, x);
        if(r > mid) mul(rc, l, r, x);
        pushup(k);
    }

    double query(int k, int l, int r){
        if(l <= d[k].l && d[k].r <= r){
            return d[k].dat;
        }
        pushdown(k); double sum = 0;
        int mid = (d[k].l + d[k].r) >> 1;
        if(l <= mid) sum = (sum + query(lc, l, r));
        if(r > mid) sum = (sum + query(rc, l, r));
        return sum;
    }

}Seg;

int n, m;

int main(){

	//freopen("random.in", "r", stdin);freopen("random.out", "w", stdout);
    scanf("%d%d", &n, &m);
    for(int i = 1; i <= n; i ++) scanf("%lf", &tmp[i]);
    Seg.build(1, 1, n);
    while(m--){
        int opt, l1, r1, l2, r2; ll x;
        scanf("%d", &opt);
        if(opt == 1){
            scanf("%d%d%d%d", &l1, &r1, &l2, &r2);
           	double d1 = Seg.query(1, l1, r1);
         	double d2 = Seg.query(1, l2, r2);
           	Seg.mul(1, l1, r1, double(r1 - l1) / double(r1 - l1 + 1));
         	Seg.mul(1, l2, r2, double(r2 - l2) / double(r2 - l2 + 1));
			Seg.add(1, l1, r1, d2 / double(r1 - l1 + 1) / double(r2 - l2 + 1));
         	Seg.add(1, l2, r2, d1 / double(r2 - l2 + 1) / double(r1 - l1 + 1));
        }
        if(opt == 2){
            scanf("%d%d", &l1, &r1);
            printf("%.8lf\n", Seg.query(1, l1, r1));
        }
    }
    return 0;
}

mycode

#include<cmath>
#include<cstdio>
#include<iostream>
#include<algorithm>
inline int read() {
	int x = 0 ,f = 1;
	char c = getchar();
	while(c > '9' || c < '0') c = getchar();
	while(c <= '9' && c >= '0') x = x * 10 + c - '0',c = getchar();
	return x * f;
} 

int n,m;
#define double long double
const int maxn = 2000007;
int a[maxn];
double t[maxn << 1] ;
 double tag[maxn << 1];
int tagl[maxn << 1],tagr[maxn << 1]; 

void update(int x) {
	t[x] = t[x << 1] + t[x << 1 | 1];
} 

double merge(double c1,double c2,int l,int r,int t1,int t2) {
	double k1 = 1.0 * r - l + 1, k2 = 1.0 * t2;
	return c1 * (k1 - 1) / k1 + c2 /t2 ;
} 

void pushdown(int x,int l,int r) {
	int mid = l + r >> 1; 

	t[x << 1] = merge(t[x << 1] , tag[x] , l , mid , tagl[x] , tagr[x]); 

	t[x << 1 | 1] = merge(t[x << 1 | 1] , tag[x] , mid + 1,r , tagl[x] , tagr[x]); 

	tag[x << 1] = tag[x << 1 | 1] = tag[x];
	tagl[x << 1] = tagl[x << 1 | 1] = tagl[x];
	tagr[x << 1] = tagr[x << 1 | 1] = tagr[x];
	tagl[x] = tagr[x] = 0; tag[x] = 0.0;
} 

void build(int x,int l,int r) {
	if(l == r) { t[x] = a[l]; return; } 

	int mid = l + r >> 1; 

	build(x << 1,l,mid); build(x << 1 | 1,mid + 1,r);
	update(x);
}
double Query(int x,int l,int r,int L,int R) {
	if(tag[x] != 0.0 && tagl[x] && tagr[x]) pushdown(x,l,r);
	if(l >= L && r <= R)  return t[x];  

	double ret = 0;
	int mid = l + r >> 1;
	if(L <= mid) ret += Query(x << 1,l,mid,L,R);
	if(R > mid ) ret += Query(x << 1 | 1,mid + 1,r,L,R);
	return ret;
	//update(x);
}
void modify(int x,int l,int r,int L,int R,double CC,int t1,int t2) { 

	if(tag[x] != 0.0&& tagr[x] && tagl[x]) pushdown(x,l,r);
	if(l >= L && r <= R) {
		t[x] = merge(t[x],CC,l,r,t1,t2);
		if(l != r) {
			tag[x] = CC;
			tagl[x] = t1;
			tagr[x] = t2;
		}
		return ;
	}
	int mid = l + r >> 1;
	if(L <= mid) modify(x << 1,l,mid,L,R,CC, t1,t2);
	if(R > mid ) modify(x << 1 | 1,mid + 1,r,L,R, CC,t1,t2);
	update(x);
}
int main() {
	//freopen("random.in","r",stdin);  freopen("random.out","w",stdout);
	n = read(),m = read();
	for(int i = 1;i <= n;++ i) a[i] = read();  

	build(1,1,n);
	for(int type,l,r,l1,r1,i = 1;i <= m;++ i) {
		type = read();
		if(type == 1) {
			l = read(),r = read();
			l1 = read();r1 = read();
			double q1 = Query(1,1,n,l,r);
			double q2 = Query(1,1,n,l1,r1);
			modify(1,1,n,l,r,q2 , r - l + 1 , r1 - l1 + 1);
			modify(1,1,n,l1,r1,q1 , r1 - l1 + 1 , r - l + 1);
		}
		else {
			l = read(),r = read();
			//printf("%llf\n",Query(1,1,n,l,r));
			std::cout << Query(1,1,n,l,r) << std::endl;
		}
	}
	return 0;
}
/*
4 4
1 1 2 2
1 2 2 3 3
2 1 2
1 1 2 3 4
2 1 2
*/