Find the nondecreasing subsequences HDU 2227

本文主要是介绍Find the nondecreasing subsequences HDU 2227，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

树状数组

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define maxn 100006
int a[maxn];
int n=maxn;
struct Note
{
int val,ord;
}b[maxn];
bool cmp(Note a,Note b)
{
return a.val<b.val;
}
int lowbit(int i)
{
return i&(-i);
}
int Sum(int i)
{
int sum=0;
while(i>=1)
{
sum=(sum+a[i])%1000000007;
i-=lowbit(i);
}
return sum;
}
void Update(int i,int tem)
{
while(i<=n)
{
a[i]+=tem;
a[i]=a[i]%1000000007;
i+=lowbit(i);
}
}
int main()
{
int m;
int i;
int c[maxn];
int k;
while(scanf("%d",&m)!=EOF)
{
for(i=1;i<=m;i++)
{
scanf("%d",&b[i].val);
b[i].ord=i;
}
sort(b+1,b+m+1,cmp);
memset(a,0,sizeof(a));
c[b[1].ord]=1;
for(i=2;i<=m;i++)//因为数值范围是2^32,所以做了个小处理，按照排序把数值缩小。
{
if(b[i].val>b[i-1].val)
c[b[i].ord]=i;
else
c[b[i].ord]=c[b[i-1].ord];
}
for(i=1;i<=m;i++)
{
k=Sum(c[i]);
Update(c[i],k+1);
}
printf("%d\n",Sum(m));
}
return 0;
}

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