G , , , ; : c(G).
c()=n-1; c()=1; c()=2.
G , ; : .
l()=n-1; l()=1; l()=2.
0.
:
v G , , G\{v} , G.
G , .
:
, .
.
. - G, : c(G) .
:
;
: {c,d,e},{c,b,f},{a,g,h,i},{a,b}.
G=(V,E), (), . s Î V t Î V , . , . , .
:
- s ;
- .
. (n,m)- ( ), ..:
s .
, s . , . , , s .
.
l(xi) xi, () , .
1. .
l(s)=0 . l(xi)=¥ xi ≠s . p=s.
2. .
xi Î(), , :
l(xi)=min[l(xi),l(p)+c(p,xi)]. (1)
|
|
3. .
,
l(xi*)=min[l(xi)].
4. xi* ; = xi*.
5. =t, l(p) . .
¹t, 2.
. ,
L(xi)+c(xi, xi)=L(xi);
.. xi xi s xi, xi xi .
:
G:
∞ | ∞ | ||||||
∞ | ∞ | ∞ | |||||
∞ | |||||||
∞ | ∞ | ∞ | |||||
∞ | |||||||
∞ | |||||||
∞ |
1 .
1) l(1) = 0;
l(2) = l(3) = = l(7) =∞;
p = 1.
2) (1) = {3,5,6,7};
l(3) = min(l(3), l(1)+C(1,3)) = min(∞,0+4)=4;
l(5) = min(l(5), l(1)+C(1,5)) = 16;
l(6) = min(l(2), l(1)+C(1,2)) = 14;
l(7) = min(l(2), l(1)+C(1,2)) = 2.
3) min(4,16,14,2) = 2;
min = l(7) = 2;
p = 7.
4) (7) ={1,2,3,5,6};
l(2) = min(l(2), l(7)+C(2,7)) = min(∞, 2+9)=11;
l(3) = min(l(3), l(7)+C(3,7)) = 4;
l(5) = min(l(5), l(7)+C(5,7)) =16;
l(6) = min(l(6), l(7)+C(6,7)) = 14.
5) min(11,4,16,14) = 4;
min = l(3) = 4;
p = 3.
6) (3) = {1,4,5,6,7};
l(4) = min(l(4), l(3)+C(4,3)) = 13;
l(5) = min(l(5), l(3)+C(5,3)) = 16;
l(6) = min(l(6), l(3)+C(6,3)) = 14.
7) min(13,16, 14) = 13;
min = l(4) = 13;
p=4.
8) (4) = {2,3,5};
l(5) = min(l(5), l(4)+C(5,4)) = 16;
l(2) = min(l(6), l(3)+C(6,3)) = 11.
9) min(11,16) = 11;
min = l(2) =11;
p = 2.
10) (2) = {4,6,7};
l(6) = min(l(6), l(2)+C(2,6)) = 14.
11) min = l(6) =14;
p = 6.
12) l(5) = min(l(5), l(6)+C(5,6)) = 16;
p=5.
, 1:
(1-2): (1,7,2)=11;
(1-3): (1,3)=4;
(1-4): (1,3,4)=(1,7,3,4)=(1,7,2,4)=13;
(1-5): (1,5)=16;
(1-6): (1,6)=14;
(1-7): (1,7)=2.
, .
2 l(x) (1) , . l(x) , , .. .
l(x), .
, , 2 l(x) .
.
lk(xi) i (k+1)- , (s) , s.
|
|
1. .
S= (s), k=1, l1(s)=0, l1(xi)=c(s, xi) xiÎ (s). l1(xi)=¥ xi.
2. .
xi Î (s) (xi¹s) :
lk+1(xi)=min[lk(xi),min{ lk(xi)+c(xj, xi)}] xjÎ Ti, Ti=(xi)ÇS.
3. .
k£n-1 lk+1(xi)= lk(xi) xi, . .
k<n-1 lk+1(xi)¹ lk(xi) xi, 4.
k=n-1 lk+1(xi)¹ lk(xi) xi, . .
4. .
:
S={xi | lk+1(xi) ¹ lk(xi)}.
5. k=k+1 2.
. . , : n , n , - : .
:
G:
∞ | ∞ | ||||||
∞ | ∞ | ∞ | |||||
∞ | |||||||
∞ | ∞ | ∞ | |||||
∞ | |||||||
∞ | |||||||
∞ |
1) s=1; , 1: S= (s)={3,5,6,7},
k=1; l1(1)=0,
l1(3)=4, l1(5)=16, l1(6)=14, l1(7)=2, l1(2)= l1(4)=¥;
2) (s)={2,3,4,5,6,7} - , 3,5,6,7;
2: 2={7,6,4}Ç{3,5,6,7}={7,6}, {7,6,4} - , 2;
l2(2)=min(¥, min(2+9,14+3))=11;
3: 3={1,4,5,6,7}Ç{3,5,6,7}={5,6,7}, {1,4,5,6,7} - , 3;
l2(3)=min(4, min(16+12,14+10,2+2))=4;
4: 4={2,3,5}Ç{3,5,6,7}={3,5}, {2,3,5} - , 4;
l2(4)=13;
5: 5={1,3,4,6,7}Ç{3,5,6,7}={3,6,7}, {1,3,4,6,7} - , 5;
l2(5)= 16;
6: 2={1,2,3,5,7}Ç{3,5,6,7}={3,5,7}, {1,2,3,5,7} - , 6;
l2(6)= 14;
7: 2={1,2,3,5,6}Ç{3,5,6,7}={3,5,6}, {1,2,3,5,6} - , 7;
l2(7)=2;
3) 4, S;
4) S={2,4};
5) k=2; 2;
6) (S)={2,3,4,5,6,7} - , 2,4;
2: 2={7,6,4}Ç{2,4}={4};
l3(2)=min(11, 13+2))=11;
3: 3={1,4,5,6,7}Ç{2,4}={4};
l3(3)=min(4, 13+9)=4;
4: 4={2,3,5}Ç{2,4}={2};
l3(4)= min(13, 11+2)=13;
5: 5={1,3,4,6,7}Ç{2,4}={4};
l3(5)= 16;
6: 2={1,2,3,5,7}Ç{2,4}={2};
l3(6)= 14;
7: 2={1,2,3,5,6}Ç{2,4}={2}
l3(7)=2.
7) k£n-1 lk+1(xi)= lk(xi) xi, , .
1:
(1-2):(1,7,2)=11;
(1-3): (1,3)=4;
(1-4): (1,3,4)=(1,7,3,4)=(1,7,2,4)=13;
(1-5): (1,5)=16;
(1-6): (1,6)=14;
(1-7): (1,7)=2.
n () . k- , xi xj ( xi xj) { x1, x2,, xn}.
|
|
G .
.
1. .
k=0.
2.
k=k+1.
3.
i ¹ k cik¹¥, j ¹k ckj ¹¥ :
cij=min[cij, (cik+ckj)]. (2)
4. .
cij <0, , xi; . .
cij ³ 0 k=n, . .
cij ³ 0, k<n, 2.
:
G :
: :
k=0;
k=1;
∞ | ∞ | ||||||
∞ | ∞ | ∞ | |||||
∞ | |||||||
∞ | ∞ | ∞ | |||||
∞ | |||||||
∞ | |||||||
∞ |
k=2;
∞ | ∞ | ||||||
∞ | ∞ | ∞ | |||||
∞ | |||||||
∞ | |||||||
∞ | |||||||
k=3;
∞ | |||||||
∞ | ∞ | ∞ | |||||
∞ | |||||||
∞ | |||||||
k=4;
|
|
k=5;
k=6;
k=7;
|
|
q=[qij] , qij , j i j. q qij= i i j. 3 :
q.
, :
:
1,7,2 | 1,3 | 1,3,4 | 1,5 | 1,6 | 1,7 | ||
2,7,1 | 2,4,3 | 2,4 | 2,4,5 | 2,6 | 2,7 | ||
3,1 | 3,4,2 | 3,4 | 3,5 | 3,6 | 3,7 | ||
4,3,1 | 4,2 | 4,3 | 4,5 | 4,2,6 | 4,2,7 | ||
5,1 | 5,4,2 | 5,3 | 5,4 | 5,6 | 5,7 | ||
6,1 | 6,2 | 6,3 | 6,2,4 | 6,5 | 6,7 | ||
7,1 | 7,2 | 7,3 | 7,2,4 | 7,5 | 7,6 |
1:
(1-2): (1,7,2)=11;
(1-3): (1,3)=4;
(1-4): (1,3,4)=(1,7,3,4)=(1,7,2,4)=13;
(1-5): (1,5)=16;
(1-6): (1,6)=14;
(1-7): (1,7)=2.
1. , , .
2. ? ?
3. , .
4. ?
5. ( )?
6. ?
7. .
8. ( 1).
9. , .
10. .