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  • hdoj 1025 Constructing Roads In JGShining's Kingdom(最长上升子序列+二分)

    题目:http://acm.hdu.edu.cn/showproblem.php?pid=1025

    View Code
     1 #include <iostream>
     2 #include<cstdio>
     3 #include<cstring>
     4 #define maxn 500010
     5 using namespace std;
     6 int a[maxn];
     7 int b[maxn];//存储序列长度为len的第i小的数中最小的数
     8 int dp[maxn];
     9 int chazhao(int x,int l,int r)//查找第i-1的长度序列中,结尾比a[i]小的最大长度
    10 {
    11     int mid;
    12     while(l<=r)
    13     {
    14         mid=(l+r)/2;
    15         if(b[mid]<=x)
    16         l=mid+1;
    17         else
    18         r=mid-1;
    19     }
    20     return r;
    21 }
    22 int main()
    23 {
    24     int x,y,i,n,k=0,len;
    25     while(scanf("%d",&n)!=EOF)
    26     {
    27         k++;
    28         for(i=0;i<n;i++)
    29         {
    30             scanf("%d%d",&x,&y);
    31             a[x]=y;
    32         }
    33         memset(b,-1,sizeof(b));
    34         dp[1]=1;
    35         b[1]=a[1];
    36         len=1;
    37         for(i=2;i<=n;i++)
    38         {
    39             int max=chazhao(a[i],1,len);
    40             dp[i]=max+1;
    41             if(b[i]==-1||b[dp[i]]>a[i])//更新b
    42             b[dp[i]]=a[i];
    43             if(len<dp[i])
    44             len=dp[i];
    45         }
    46         if(len==1)
    47         {
    48             printf("Case %d:\n",k);
    49         printf("My king, at most %d road can be built.\n\n",len);
    50         }
    51         else
    52         {
    53               printf("Case %d:\n",k);
    54         printf("My king, at most %d roads can be built.\n\n",len);
    55         }
    56 
    57     }
    58     return 0;
    59 }
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  • 原文地址:https://www.cnblogs.com/wanglin2011/p/2731634.html
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