zoj 1610 Count the Colors（线段树）

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题意：给一块长8000米的板上色问最后能看见几种颜色而每种颜色的几段

思路：线段树。这道题有很多细节
eg： 0 2 1
3 4 1
output 应该是 1 2 因为中间隔了一段空的

具体见代码

#include <stdio.h>#include <string.h>#define M 8005#define L(x) (x<<1)#define R(x) ((x<<1)+1)struct data{    int l,r,col;      //col 等于 -1 表示什么色都没有}node[M*3];int color[M];       //记录每块板上的是什么颜色void BuildTree(int left,int right,int u){    node[u].l = left;    node[u].r = right;    node[u].col = -1;    if (left == right)        return ;    int mid = (left + right)>>1;    BuildTree(left,mid,L(u));    BuildTree(mid+1,right,R(u));}void getdown(int u){    node[L(u)].col = node[u].col;    node[R(u)].col = node[u].col;    node[u].col = -1;}void updata (int left,int right,int val,int u){    if (node[u].col == val)        return ;    if (left <= node[u].l&&node[u].r <= right)    {        node[u].col = val;        return ;    }    if (node[u].col != -1)       //延迟覆盖 不然可能会TLE（最近做一直都是延迟覆盖）        getdown (u);    int mid = (node[u].l+ node[u].r)>>1;    if (right <= mid)        updata (left,right,val,L(u));    else if (left >= mid+1)        updata (left,right,val,R(u));    else    {        updata (left,right,val,L(u));        updata (left,right,val,R(u));    }    if ((node[L(u)].col == node[R(u)].col)&&node[L(u)].col != -1)  //递归回来修改父结点颜色        node[u].col = node[L(u)].col;}void query (int u){    if (node[u].col != -1)    {        for (int i = node[u].l;i <= node[u].r;i ++)            color[i] = node[u].col;        return ;    }    if (node[u].l == node[u].r)   //这是不加这个竟然会运行不起来        return ;    query (L(u));    query (R(u));}void ans (){    int res[M];    memset (res,0,sizeof(res));    int pre = -1,i;    for (i = 0;i < M;i ++)        if (pre != color[i]) //颜色块不相连就++        {            pre = color[i];            res[pre] ++;        }    for (i = 0;i < M;i ++)        if (res[i] !=0)            printf ("%d %d\n",i,res[i]);    printf ("\n");}int main (){    int n,x,y,val;    while (~scanf ("%d",&n))    {        memset (color,-1,sizeof (color));        BuildTree(0,M,1);        while (n --)        {            scanf ("%d%d%d",&x,&y,&val);            if (x == y)                continue;            updata (x,y-1,val,1);   //后面一个不涂就能避免那种情况        }        query (1);        ans();    }    return 0;}

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