HDU 1160 FatMouse's Speed (动态规划最长下降子序列)
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FatMouse‘s Speed
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 24573 Accepted Submission(s): 10896
Special Judge
Problem Description
Input
The data for a particular mouse will consist of a pair of integers: the first representing its size in grams and the second representing its speed in centimeters per second. Both integers are between 1 and 10000. The data in each test case will contain information for at most 1000 mice.
Two mice may have the same weight, the same speed, or even the same weight and speed.
Output
Your
program should output a sequence of lines of data; the first line
should contain a number n; the remaining n lines should each contain a
single positive integer (each one representing a mouse). If these n
integers are m[1], m[2],..., m[n] then it must be the case that
W[m[1]] < W[m[2]] < ... < W[m[n]]
and
S[m[1]] > S[m[2]] > ... > S[m[n]]
In order for the answer to be correct, n should be as large as possible.
All
inequalities are strict: weights must be strictly increasing, and
speeds must be strictly decreasing. There may be many correct outputs
for a given input, your program only needs to find one.
Sample Input
6008 1300 6000 2100 500 2000 1000 4000 1100 3000 6000 2000 8000 1400 6000 1200 2000 1900
Sample Output
4 4 5 9 7
题目大意与分析
给出一堆鼠标的重量与速度,输出一个最长的序列,满足重量越来越大,速度越来越小。
先将鼠标根据重量从小到大排序,再求最大下降子序列就行了。
#include<bits/stdc++.h> using namespace std; typedef struct { int add; int w; int s; }node; node a[1005]; int dp[1005],anss,i,temp,c[1005],x,y,num,j,n; bool cmp(node a,node b) { return a.w<b.w; } int main() { while(cin>>x>>y) { num++; a[num].add=num; a[num].w=x; a[num].s=y; } sort(a+1,a+1+num,cmp); for(i=1;i<=num;i++) { dp[i]=1; for(j=1;j<i;j++) { if(a[j].w<a[i].w&&a[j].s>a[i].s) dp[i]=max(dp[j]+1,dp[i]); } if(dp[i]>anss) anss=dp[i]; } cout<<anss<<endl; temp=anss; for(i=num;i>=1;i--) { if(dp[i]==temp) { temp--; c[temp]=a[i].add; } } for(i=0;i<anss;i++) cout<<c[i]<<endl; }
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