目标函数是 max z 15yLAB +15y3AB +20yLAC +20y3AC+5yBA+5y3BA+5y4BA +302BC+303BC+10y2CA+10CA+10g4CA+15y2CB+15y3cB(3.3) 第一组约束条件是第1,2,3次单程的重空车总数等于250辆（因空车不计成本，所以 宁恩放空车也不停在原地，使问题简化一些)，第3次单程到达A的车不再走，所以第4单 程车数小于250辆. 1AB+1AC=250, (3.4) T2BA+2BC +CA+CB 250, (3.5) I3AB 3AC +3BA+3BC +CA+3CB=250, (3.6) 4BA+4CA≤250. 3.7) 第二组约束条件方程是每个单程从某地出发之车数等于上一个单程到达该地的车数： Z2BA十T2BC=T1AB (3.8) T2CA+2CB FLAC 3.9) (3.10) 3BA+3BC F2CB (3.11) T3CA T3CB T2BC (3.12) EABA I3AB+3CB 3.13) EACA Z3AC +3BC. (3.14) 第三组约束条件方程是两地间的重车数小于等于运量 AB+gAB≤150， (3.15) 1AC+班AC≤250， (3.16) 2BA十为BA十BA≤100， (3.17) hBC+3BC≤200 (3.18) 2CA+CA+CA≤500， 3.19 2CB+cB≤100. (3.20) 第四组约束条件方程是两地间的重车数小于等于空重车总数 hAB≤工1AB (3.21) BAB≤3AB (3.22) hAC≤1AC, (3.23) 3AC≤T3AC, 3.24 2BA≤T2BA: (3.25)11 r ❦✁➉❉✁❭: max z = 15y1AB + 15y3AB + 20y1AC + 20y3AC + 5y2BA + 5y3BA + 5y4BA +30y2BC + 30y3BC + 10y2CA + 10y3CA + 10y4CA + 15y2CB + 15y3CB.(3.3) ❨✁❬✁➊✁➋✁➌✁➍✁➎❭ ❨ 1,2,3 ❣❶✁❷✽✁➈✁✬✇✁➥❉✁➏➂ 250 ➐ (➃✬ ✇✁✳✁✴✁✵✁✶, ❻✁❜ Ý✁Þ✁ß✬ ✇✁✲✁✳✁à✁★✁á➡ , ➷❇✁❈✁â✁ã❬✁ä), ❨ 3 ❣❶✁❷Û✁å A ✽✇✁✳✁æ✁ç, ❻✁❜✁❨ 4 ❶ ❷ ✇❉✁➢➂ 250 ➐✁✩ x1AB + x1AC = 250, (3.4) x2BA + x2BC + x2CA + x2CB = 250, (3.5) x3AB + x3AC + x3BA + x3BC + x3CA + x3CB = 250, (3.6) x4BA + x4CA ≤ 250. (3.7) ❨✟❥✟➊✟➋✟➌✟➍✟➎❙❷❭✟×❆✟❶✁❷❑✁❡➡ ⑦✟Ö✁è✟✇❉✟➏➂❰❬ ❆✁❶✟❷Û✟å✁é➡✁✽✇❉ : x2BA + x2BC = x1AB, (3.8) x2CA + x2CB = x1AC , (3.9) x3AB + x3AC = x2BA + x2CA, (3.10) x3BA + x3BC = x2CB, (3.11) x3CA + x3CB = x2BC , (3.12) x4BA = x3AB + x3CB, (3.13) x4CA = x3AC + x3BC . (3.14) ❨✁➤✁➊✁➋✁➌✁➍✁➎❙❷❭✁❋✁➡➇ ✽✁➈✇❉✁➢➂➏ ➂⑨❘ : y1AB + y3AB ≤ 150, (3.15) y1AC + y3AC ≤ 250, (3.16) y2BA + y3BA + y4BA ≤ 100, (3.17) y2BC + y3BC ≤ 200, (3.18) y2CA + y3CA + y4CA ≤ 500, (3.19) y2CB + y3CB ≤ 100. (3.20) ❨✁ê✁➊✁➋✁➌✁➍✁➎❙❷❭✁❋✁➡➇ ✽✁➈✇❉✁➢➂➏ ➂✬✁➈✇✁➥❉ : y1AB ≤ x1AB, (3.21) y3AB ≤ x3AB, (3.22) y1AC ≤ x1AC , (3.23) y3AC ≤ x3AC , (3.24) y2BA ≤ x2BA, (3.25)