POJ - 1177 题目
题意： 给一堆矩形，求这些矩形的周长
#include #include #include #include #include using namespace std; #define met(a,b) memset(a,b,sizeof(a)) const int maxn = 5010; struct node { int x,v,y1,y2; node(){} node(int a,int b,int c,int d) { x = a; v = b; y1 = c; y2 = d;} }X[maxn<<1]; map id; int y[maxn << 1],ylen[maxn << 1]; int cover[maxn<<3],len[maxn<<3],cnt[maxn<<3],flag[maxn<<1]; int xnum,ynum; bool cmp(node a,node b) { return a.x < b.x; } void pre() { id.clear(); met(cover,0); met(ylen,0); //离散化 sort(X, X + xnum, cmp); sort(y, y + ynum); ynum = unique(y,y+ynum) - y; for(int i = 0; i < ynum - 1; i++) { id[ y[i] ] = i + 1 ; ylen[i+1] = y[i+1] - y[i]; } id[y [ynum-1] ] = ynum; ylen[ynum] = 0; } void up(int ul,int ur,int v,int id,int l,int r) { if(r < ul || l > ur) return; if(l >= ul && r <= ur) { cover[id] += v; if(l == r) { if(cover[id]) { len[id] = ylen[l]; cnt[id] = 1; flag[l] = 1; return; } else {len[id] = 0; cnt[id] = 0; flag[l] = 0; return;} } } int m = l+r>>1; if(ul <= m) up(ul,ur,v,id<<1,l,m); if(ur > m) up(ul,ur,v,id<<1|1,m+1,r); len[id] = len[id<<1] + len[id<<1|1]; cnt[id] = cnt[id<<1] + cnt[id<<1|1]; if(flag[m] && flag[m+1]) cnt[id]--; } int main() { int n; while(~scanf("%d",&n)) { xnum = 0, ynum = 0; for(int i = 0; i < n ; i++) { int a,b,c,d; scanf("%d%d%d%d",&a,&b,&c,&d); X[xnum++] = node(a,1,b,d); X[xnum++] = node(c,-1,b,d); y[ynum++] = b, y[ynum++] = d; } pre(); //离散化处理 int ret = 0; int last = 0,lastnum = 0; for(int i = 0; i < xnum; i++) { int id1 = id[X[i].y1] , id2 = id[X[i].y2]; up(id1,id2-1,X[i].v,1,1,ynum); int th = abs(len[1]-last); if(i) th += lastnum*2*(X[i].x-X[i-1].x); lastnum = cnt[1]; //cout<< th <<" "<< cnt[1] << endl; ret += th; last = len[1]; } printf("%d\n",ret); } return 0; }
