POJ2777(线段树)

color为－1时表示这一段的区间内有不同的颜色，需要继续遍历其左子树和右子树。

线段树的构造用了如下所示的方式。

线段树相关知识：http://www.cnblogs.com/shuaiwhu/archive/2012/04/22/2464583.html

                                http://hi.baidu.com/semluhiigubbqvq/item/be736a33a8864789f4e4ad18

#include <iostream>#include <algorithm>#include <map>#include <cstdio>using namespace std;struct Node{  int left;int right;Node *leftchild;Node *rightchild;int color;};Node* build(int l,int r){  Node* root=new Node;root->left=l;root->right=r;root->leftchild=NULL;root->rightchild=NULL;root->color=1;if (l+1<r){int mid=(r+l)>>1;root->leftchild=build(l,mid);root->rightchild=build(mid,r);}return root;}void Insert(int begin,int end,Node* root,int color){if (begin<=root->left && end>=root->right){if (root->color!=-1 && root->leftchild!=NULL && root->rightchild!=NULL){root->leftchild->color=root->color;root->rightchild->color=root->color;}root->color=color;}else{if (root->color!=-1 && root->leftchild!=NULL && root->rightchild!=NULL){root->leftchild->color=root->color;root->rightchild->color=root->color;}root->color=-1;if (begin<(root->left+root->right)/2) Insert(begin,end,root->leftchild,color);if (end>(root->left+root->right)/2) Insert(begin,end,root->rightchild,color);}}int Traversal(int begin,int end,Node* root,int* record){if (root->color!=-1){    if (record[root->color]==0)  {  record[root->color]=1;      return 1;  }  else  return 0;}else{if (begin<(root->left+root->right)/2 && end>(root->left+root->right)/2)return Traversal(begin,end,root->leftchild,record)+Traversal(begin,end,root->rightchild,record);else if (begin<(root->left+root->right)/2 && end<=(root->left+root->right)/2)return Traversal(begin,end,root->leftchild,record);else if (begin>=(root->left+root->right)/2 && end>(root->left+root->right)/2)return Traversal(begin,end,root->rightchild,record);elsereturn 0;}}int main(){  int L,T,O;cin >> L >> T >> O;getchar();Node* root=build(1,L+1);int i;char c;int begin;int end;int color;int total=0;for (i=1;i<=O;i++){int record[31]={0};scanf("%c",&c);if (c=='C'){  scanf("%d%d%d",&begin,&end,&color);getchar();Insert(begin,end+1,root,color);}else{scanf("%d%d",&begin,&end);getchar();total=Traversal(begin,end+1,root,record);printf("%d\n",total);}}return 0;}