poj2181

简单dp

View Code

   
     

    
      #include 
    
      <
    
      iostream
    
      >
    
      
#include 
    
      <
    
      cstdlib
    
      >
    
      
#include 
    
      <
    
      cstring
    
      >
    
      
#include 
    
      <
    
      cstdio
    
      >
    
      

    
      using
    
       
    
      namespace
    
       std;


    
      int
    
       n, even, odd;


    
      int
    
       main()
{

    
      //
    
       freopen("t.txt", "r", stdin);
    
      

    
       scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      n);
 
    
      if
    
       (n 
    
      ==
    
       
    
      1
    
      )
 {
 
    
      int
    
       a;
 scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      a);
 printf(
    
      "
    
      %d\n
    
      "
    
      , a);
 
    
      return
    
       
    
      0
    
      ;
 }
 scanf(
    
      "
    
      %d%d
    
      "
    
      , 
    
      &
    
      odd, 
    
      &
    
      even);
 
    
      int
    
       a, temp;
 temp 
    
      =
    
       even;
 even 
    
      =
    
       odd 
    
      -
    
       even;
 odd 
    
      =
    
       max(temp, odd);
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      2
    
      ; i 
    
      <
    
       n; i
    
      ++
    
      )
 {
 scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      a);
 temp 
    
      =
    
       max(odd, even 
    
      +
    
       a);
 even 
    
      =
    
       max(even, odd 
    
      -
    
       a);
 odd 
    
      =
    
       temp;
 }
 printf(
    
      "
    
      %d\n
    
      "
    
      , max(even, odd));
 
    
      return
    
       
    
      0
    
      ;
}