📄 cupiticy.mht
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<p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:22.0pt;font-fami=
ly:LiSu;
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<v:formulas>
<v:f eqn=3D"if lineDrawn pixelLineWidth 0"/>
<v:f eqn=3D"sum @0 1 0"/>
<v:f eqn=3D"sum 0 0 @1"/>
<v:f eqn=3D"prod @2 1 2"/>
<v:f eqn=3D"prod @3 21600 pixelWidth"/>
<v:f eqn=3D"prod @3 21600 pixelHeight"/>
<v:f eqn=3D"sum @0 0 1"/>
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<v:f eqn=3D"prod @7 21600 pixelWidth"/>
<v:f eqn=3D"sum @8 21600 0"/>
<v:f eqn=3D"prod @7 21600 pixelHeight"/>
<v:f eqn=3D"sum @10 21600 0"/>
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</v:shape><![endif]--><![if !vml]><img width=3D763 height=3D187
src=3D"file0741.files/image003.jpg" v:shapes=3D"_x0000_i1032"><![endif]><o:=
p></o:p></span></p>
<p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:22.0pt;font-fami=
ly:LiSu;
color:#993366'><!--[if gte vml 1]><v:shape id=3D"_x0000_i1031" type=3D"#_x0=
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</v:shape><![endif]--><![if !vml]><img width=3D758 height=3D176
src=3D"file0741.files/image005.jpg" v:shapes=3D"_x0000_i1031"><![endif]><o:=
p></o:p></span></p>
<p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:22.0pt;font-fami=
ly:LiSu;
color:#993366'>2:</span><span style=3D'font-size:22.0pt;font-family:LiSu;
color:#993366'>抽象化控制<span lang=3DEN-US>:=
<o:p></o:p></span></span></p>
<p class=3DMsoNormal style=3D'text-indent:110.0pt;mso-char-indent-count:5.0=
'><span
lang=3DEN-US style=3D'font-size:22.0pt;font-family:LiSu;color:#993366'><!--=
[if gte vml 1]><v:shape
id=3D"_x0000_i1030" type=3D"#_x0000_t75" style=3D'width:331.5pt;height:275=
.25pt'>
<v:imagedata src=3D"file0741.files/image006.jpg" o:title=3D"8"/>
</v:shape><![endif]--><![if !vml]><img width=3D442 height=3D367
src=3D"file0741.files/image007.jpg" v:shapes=3D"_x0000_i1030"><![endif]><o:=
p></o:p></span></p>
<p class=3DMsoNormal><span style=3D'font-size:22.0pt;font-family:LiSu;color=
:red'>二<span
lang=3DEN-US>:</span>重要问题<span lang=3DEN-US>--<=
/span>怎样选取贪心机制<span
lang=3DEN-US>?<o:p></o:p></span></span></p>
<p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:22.0pt;font-fami=
ly:LiSu;
color:#993366'>1:</span><span style=3D'font-size:22.0pt;font-family:LiSu;
color:#993366'>重要性<span lang=3DEN-US>:<o:p></o:p></spa=
n></span></p>
<p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:22.0pt;font-fami=
ly:LiSu;
color:black'><span style=3D'mso-spacerun:yes'> </span></span><s=
pan
style=3D'font-size:22.0pt;font-family:LiSu;color:black'>以前=
2825;讲的投资问题为例<span
lang=3DEN-US>: </span>如果把问题数é=
83;改变<span
lang=3DEN-US>:<o:p></o:p></span></span></p>
<p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:22.0pt;font-fami=
ly:LiSu;
color:black'>A(20,20),B(19,18),C(10,1),D(5,1)</span><span style=3D'font-siz=
e:
22.0pt;font-family:LiSu;color:black'>总金额为<span
lang=3DEN-US>38 Y,</span>无论我们以收&#=
30410;额还是收益率为贪õ=
15;条件都不能得到</span><u><span
style=3D'font-size:22.0pt;font-family:LiSu;color:teal'>最优#=
299;</span></u><span
lang=3DEN-US style=3D'font-size:22.0pt;font-family:LiSu;color:black'>.</spa=
n><span
style=3D'font-size:22.0pt;font-family:LiSu;color:black'>当我=
0204;想用贪心法求最优෉=
9;时<span
lang=3DEN-US>,</span>我们必须考虑ৎ=
5;们的</span><u><span
style=3D'font-size:22.0pt;font-family:LiSu;color:teal'>贪心=
934;则</span></u><span
style=3D'font-size:22.0pt;font-family:LiSu;color:black'>是否=
9982;</span><u><span
style=3D'font-size:22.0pt;font-family:LiSu;color:teal'>全局=
033;益</span></u><span
style=3D'font-size:22.0pt;font-family:LiSu;color:black'>相矛=
0462;<span
lang=3DEN-US>.<o:p></o:p></span></span></p>
<p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:22.0pt;font-fami=
ly:LiSu;
color:#993366'>2:</span><span style=3D'font-size:22.0pt;font-family:LiSu;
color:#993366'>举例说明<span lang=3DEN-US>:<o:p></o=
:p></span></span></p>
<p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:22.0pt;font-fami=
ly:LiSu;
color:#339966'>Eg1:</span><span style=3D'font-size:22.0pt;font-family:LiSu;
color:#339966'>钓鱼</span><span lang=3DEN-US style=3D'font-size=
:16.0pt;
font-family:LiSu;color:red'>(</span><span style=3D'font-size:16.0pt;font-fa=
mily:
LiSu;color:red'>算法艺术与信息=
3398;竞赛<span
lang=3DEN-US>P13,</span>例题<span lang=3DEN-US>1)</span></span>=
<span
lang=3DEN-US style=3D'font-size:22.0pt;font-family:LiSu;color:black'><o:p><=
/o:p></span></p>
<p class=3DMsoNormal><span style=3D'font-size:22.0pt;font-family:LiSu;color=
:black'>在一条水平路边<span
lang=3DEN-US>,</span>有<span lang=3DEN-US>n(2<b style=3D'mso-bidi-fon=
t-weight:
normal'><=3D</b>n<b style=3D'mso-bidi-font-weight:normal'><=3D</b>25)=
</span>个钓鱼湖<span
lang=3DEN-US>,</span>从左到右为<span lang=3DE=
N-US>1,2,3</span></span><b
style=3D'mso-bidi-font-weight:normal'><span lang=3DEN-US style=3D'font-size=
:22.0pt;
mso-ascii-font-family:LiSu;mso-fareast-font-family:LiSu;color:black'>…=
;</span></b><span
lang=3DEN-US style=3D'font-size:22.0pt;font-family:LiSu;color:black'>n.</sp=
an><span
style=3D'font-size:22.0pt;font-family:LiSu;color:black'>佳<span
class=3DGramE>佳</span>有<span lang=3DEN-US>H</span>个=
3567;时的空余时间<span
lang=3DEN-US>,</span>他希望用这些ਲ=
2;间钓鱼<span
lang=3DEN-US>.</span>他从<span lang=3DEN-US>1</span>出=
1457;<span
lang=3DEN-US><o:p></o:p></span></span></p>
<p class=3DMsoNormal><span style=3D'font-size:22.0pt;font-family:LiSu;color=
:black'>向右走<span
lang=3DEN-US>,</span>有选则的在一ߜ=
3;湖边停留一定时间钓&=
#40060;<span
lang=3DEN-US>,</span>最后在某个湖๟=
3;结束钓鱼<span
lang=3DEN-US>.</span>他测出<span lang=3DEN-US>,</span>=
0174;第<span
class=3DSpellE><span lang=3DEN-US>i</span></span>个湖到&#=
31532;<span
lang=3DEN-US>i+1</span>个湖要走<span lang=3DEN-US>5=
*T</span></span><b
style=3D'mso-bidi-font-weight:normal'><span lang=3DEN-US style=3D'font-size=
:14.0pt;
font-family:LiSu;color:black'>i</span></b><span style=3D'font-size:22.0pt;
font-family:LiSu;color:black'>分钟的路<span lang=3D=
EN-US>.</span>他还<span
class=3DGramE>测出第</span><span class=3DSpellE><span lan=
g=3DEN-US>i</span></span>个湖边第一个<s=
pan
lang=3DEN-US>5</span>分钟可钓鱼<span class=3D=
SpellE><span
lang=3DEN-US>F</span><b style=3D'mso-bidi-font-weight:normal'><span lang=3D=
EN-US
style=3D'font-size:14.0pt'>i</span></b></span><span lang=3DEN-US><o:p></o:p=
></span></span></p>
<p class=3DMsoNormal><span style=3D'font-size:22.0pt;font-family:LiSu;color=
:black'>以后每<span
lang=3DEN-US>5</span>分钟鱼量减少<span
class=3DSpellE><span lang=3DEN-US>D</span><b style=3D'mso-bidi-font-weight:=
normal'><span
lang=3DEN-US style=3D'font-size:14.0pt'>i</span></b></span><span lang=3DEN-=
US>.</span>假定没有其他人钓=
鱼<span
lang=3DEN-US>,</span>也不受其他因ಃ=
2;影响<span
lang=3DEN-US>,</span>编程求出钓鱼ੌ=
8;多的方案<span
lang=3DEN-US>.<o:p></o:p></span></span></p>
<p class=3DMsoNormal><span lang=3DEN-US style=3D'font-size:22.0pt;font-fami=
ly:LiSu;
color:red'><</span><span style=3D'font-size:22.0pt;font-family:LiSu;
color:red'>等价简化<span lang=3DEN-US>>:<o:p></o=
:p></span></span></p>
<p class=3DMsoNormal><span style=3D'font-size:22.0pt;font-family:LiSu;color=
:black'>先把路上用时<span
lang=3DEN-US>T=3DT</span></span><b style=3D'mso-bidi-font-weight:normal'><s=
pan
lang=3DEN-US style=3D'font-size:14.0pt;font-family:LiSu;color:black'>1</spa=
n></b><span
lang=3DEN-US style=3D'font-size:22.0pt;font-family:LiSu;color:black'>+T</sp=
an><b
style=3D'mso-bidi-font-weight:normal'><span lang=3DEN-US style=3D'font-size=
:12.0pt;
font-family:LiSu;color:black'>2</span></b><span lang=3DEN-US style=3D'font-=
size:
22.0pt;font-family:LiSu;color:black'>+</span><b style=3D'mso-bidi-font-weig=
ht:
normal'><span lang=3DEN-US style=3D'font-size:22.0pt;mso-ascii-font-family:=
LiSu;
mso-fareast-font-family:LiSu;color:black'>…</span></b><span lang=3DEN=
-US
style=3D'font-size:22.0pt;font-family:LiSu;color:black'>+T</span><span
lang=3DEN-US style=3D'font-size:14.0pt;font-family:LiSu;color:black'>i</spa=
n><span
style=3D'font-size:22.0pt;font-family:LiSu;color:black'>先算=
0986;来<span
lang=3DEN-US>.</span>就可以认为他ࡤ=
7;从一个湖到另一个瞬&=
#38388;转移<span
lang=3DEN-US>,</span>即在任意时刻๿=
7;可以从湖<span
lang=3DEN-US>1</span>到<span lang=3DEN-US>X</span>任选=
9968;个钓鱼<span
lang=3DEN-US>,</span>这样我们每次๿=
7;可以选于最多的湖</span><s=
pan
lang=3DEN-US style=3D'font-size:16.0pt;font-family:LiSu;color:black'>(</spa=
n><span
style=3D'font-size:16.0pt;font-family:LiSu;color:black'>贪心=
0934;则<span
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