hdu 1541 stars~~線段樹版~~嘻嘻

#include<stdio.h><br />#include<string.h><br />#define L 32000<br />#define N 15000<br />struct node{<br /> int l;<br /> int r;<br /> int sum;<br />};</p><p>node tree[3*L];<br />int count[N] = {0};<br />int n;</p><p>void buid_tree(int k,int left,int right)<br />{<br />int mid;<br />tree[k].l = left; tree[k].r = right;<br />if(right-left == 1){<br />tree[k].sum = 0;<br />return ;<br />}<br />mid = (left+right)/2;<br />buid_tree(2*k,left,mid);<br />buid_tree(2*k+1,mid,right);<br />tree[k].sum = tree[2*k].sum+tree[2*k+1].sum;<br />return ;<br />}</p><p>void tree_insert(int k,int left,int right)<br />{<br />int mid;<br />if(left <= tree[k].l && right >= tree[k].r){<br />tree[k].sum += 1;<br />return ;<br />}<br />mid = (tree[k].l+tree[k].r)/2;<br />if(left < mid) tree_insert(2*k,left,right);<br />if(right > mid) tree_insert(2*k+1,left,right);<br />tree[k].sum = tree[2*k].sum+tree[2*k+1].sum;<br />return ;<br />}</p><p>int get_sum(int k,int left,int right)<br />{<br />int mid;<br />int ls = 0,rs = 0;<br />if(left <= tree[k].l && right >= tree[k].r){<br /> return tree[k].sum;<br />}<br />mid = (tree[k].l+tree[k].r)/2;<br />if(left < mid) ls = get_sum(2*k,left,right);<br />if(right > mid) rs = get_sum(2*k+1,left,right);<br />return ls+rs;<br />}</p><p>int main()<br />{<br />int i,j;<br />int x,y;<br />while(scanf("%d",&n) == 1){<br />buid_tree(1,0,L+1);<br />memset(count,0,sizeof(count));<br /> for(i = 0;i < n;i++){<br /> scanf("%d %d",&x,&y);<br />count[get_sum(1,0,x+1)]++;<br />tree_insert(1,x,x+1);<br />}<br />for(i = 0;i < n;i++){<br /> printf("%d/n",count[i]);<br />}<br />}<br />return 0;<br />}</p><p>//第二道線段樹的題，別人都說是水題，不過我真的做得好吃力哦<br />//一個是因為對線段樹的一些操作還不熟，第二個是還是沒有真正理解線段樹的本質！