Hdu-2955 (01 backpack + reverse thinking + questions)

Question link: http://acm.hdu.edu.cn/showproblem.php? PID = 1, 2955

Train of Thought: note that P and M [I] are the probability of being caught and cannot be used directly. They need to be converted to the probability of escaping, and then the obtained money is regarded as the volume of the backpack and then solved.

#include<iostream>#include<cstdio>#include<cstring>using namespace std;double p,vol[120],dp[12000]; int n,t,cost[120];int main(void){    int i,j,sum;    cin>>t;    while(t--)    {        memset(dp,0,sizeof(dp));        sum=0;        dp[0]=1;        cin>>p>>n;        p=1.0-p;        for(i=0;i<n;i++) cin>>cost[i]>>vol[i],sum+=cost[i],vol[i]=1.0-vol[i];        for(i=0;i<n;i++)        {            for(j=sum;j>=cost[i];j--)            dp[j]=max(dp[j],dp[j-cost[i]]*vol[i]);        }        for(i=sum;i>=0;i--)        {            if(dp[i]>=p) break;        }        cout<<i<<endl;    }    return 0;}

 

Hdu-2955 (01 backpack + reverse thinking + questions)