【bzoj 3809】Gty的二逼妹子序列 题解&代码（c++)

题目链接：

http://www.lydsy.com/JudgeOnline/problem.php?id=3809

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题解：
bzoj脸太黑，蜜汁超时，具体算法是莫队+分块，唉

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代码：（超时的代码）

#include<iostream>#include<algorithm>#include<string.h>#include<stdio.h>#include<math.h>#define maxn (100005)#define maxm (1000005)using namespace std;int len;struct node{    int l,r;    int a,b;    int id;}q[maxm];int cmp(node x,node y){    int idx=x.l/len;    int idy=y.l/len;    if (idx!=idy)    return idx<idy;    else return x.r<y.r;}int n,m,s[maxn],ans[maxm],sq[maxn],cnt[maxn],k[maxn];int f(int x,int y){    int ans=0;    int X=sq[x];    int Y=sq[y];    if (sq[x]==sq[y])    {        for (int i=x;i<=y;i++)        if (cnt[i]>0)   ans++;        return ans;    }    while(X==sq[x])    {        if (cnt[x]>0) ans++;        x++;    }    while(Y==sq[y])    {        if (cnt[y]>0) ans++;            y--;    }    for (int i=sq[x];i<=sq[y];i++) ans+=k[i];    return ans;}int main(){    scanf("%d%d",&n,&m);    for (int i=1;i<=n;i++)    scanf("%d",&s[i]);    len=sqrt(n);    for (int i=1;i<=m;i++)    {        scanf("%d%d%d%d",&q[i].l,&q[i].r,&q[i].a,&q[i].b);        q[i].id=i;    }    for (int i=1;i<=n;i++)    sq[i]=(i-1)/len+1;    sort(q+1,q+1+m,cmp);    int nowL=0,nowR=0;    for (int i=1;i<=m;i++)    {        node now=q[i];        while (now.l > nowL)        {            cnt[s[nowL]]--;            if (cnt[s[nowL]]==0) k[sq[s[nowL]]]--;            nowL++;        }        while(now.l < nowL)        {            nowL--;            cnt[s[nowL]]++;            if (cnt[s[nowL]]==1) k[sq[s[nowL]]]++;        }        while(now.r < nowR)        {            cnt[s[nowR]]--;            if (cnt[s[nowR]]==0) k[sq[s[nowR]]]--;            nowR--;        }        while(now.r > nowR)        {            nowR++;            cnt[s[nowR]]++;            if (cnt[s[nowR]]==1) k[sq[s[nowR]]]++;        }        ans[now.id]=f(now.a,now.b);    }    for (int i=1;i<=m;i++)    printf("%d\n",ans[i]);}