模板，线段树，矩形轮廓周长

// poj 1177 矩形轮廓周长
// by utoppia

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

#define lson (u<<1)
#define rson ((u<<1)+1)
#define nMax 40010

int len[nMax<<2],cov[nMax << 2],cnt[nMax << 2],lcov[nMax<<2],rcov[nMax<<2];
struct Node{
int l,r,m;
void build(int a,int b){
l=a,r=b;
m = (l+r) >> 1;
}
} node[nMax << 2];

void setlen(int u) {
if(cov[u]>0) {
len[u] = node[u].r - node[u].l;
lcov[u] = rcov[u] = 1;
cnt[u] = 1;
return ;
}
if(node[u].r == node[u].l+1) {
len[u]=0;
lcov[u]=rcov[u]=cnt[u]=0;
}else {
len[u] = len[lson] + len[rson];
lcov[u] = lcov[lson];
rcov[u] = rcov[rson];
cnt[u] = cnt[lson]+cnt[rson]-rcov[lson]*lcov[rson];
}

}
void build(int u,int l,int r){
node[u].build(l,r);
cov[u] = len[u] = cnt[u] = lcov[u] = rcov[u] = 0;
if(l+1 == r) return ;
int m = (l+r) >> 1;
build(lson,l,m);
build(rson,m,r);
}
void ins(int u,int l,int r,int k) {
if(node[u].l==l && node[u].r==r) {
cov[u]+=k;
setlen(u);
return ;
}
int m = node[u].m;
if(r<=m) ins(lson,l,r,k);
else if(l>=m) ins(rson,l,r,k);
else {
ins(lson,l,m,k);
ins(rson,m,r,k);
}
setlen(u);
}
struct Seg{
int x[2],y,flag;
void set(int x1,int x2,int _y,int k) {
x[0]=x1;x[1]=x2;y=_y;flag=k;
}
bool operator < (const Seg& a) const { return y < a.y;}
} seg[nMax];

int const inf = 10010;
int inline max(int x,int y){ return x > y ? x : y; }
int inline abs(int x) { if(x<0) x=-x;return x;}

int n,xl,xr,yl,yr;
int main() {
while(~scanf("%d",&n)){
int m = 0;
int L = 0;
for(int i=0;i<n;i++) {
scanf("%d%d%d%d",&xl,&yl,&xr,&yr);
xl += inf;
xr += inf;
L = max(L,xl);L = max(L,xr);
seg[m++].set(xl,xr,yl,1);
seg[m++].set(xl,xr,yr,-1);
}
build(1,0,L);
sort(seg,seg+m);
int now = 0,ans=0;
for(int i=0;i<m-1;i++) {
ins(1,seg[i].x[0],seg[i].x[1],seg[i].flag);
ans += abs(len[1]-now);
ans += 2*(seg[i+1].y-seg[i].y)*cnt[1];
now = len[1];
}
ins(1,seg[m-1].x[0],seg[m-1].x[1],seg[m-1].flag);
ans += abs(len[1]-now);
printf("%d\n",ans);
}
return 0;
}