一：动态规划
1）动态规划的向前处理法
java中没有指针，所以邻接表的存储需要转化一中形式，用数组存储邻接表
用三个数组u,v,w存储边，u数组代表起点，v数组代表终点，w代表权值;例如：1-->2 权值为9 存为：u[i]=1,v[i]=2,w[i]=9,如果该边为第一条边则i=1;
package dynamicProgramming;
public class FGRAPH {
public static void main(String[] args) {
// TODO Auto-generated method stub
int i;
int first[],next[];
int n=12;
int m=21;
int[] u={0,1,1,1,1,2,2,2,3,3,4,5,5,6,6,7,7,8,8,9,10,11};
int[] v={0,2,3,4,5,6,7,8,6,7,8,7,8,9,10,9,10,10,11,12,12,12};
int[] w={0,9,7,3,2,4,2,1,2,7,11,11,8,6,5,4,3,5,6,4,2,5};
first=new int[n+2];
next=new int[m+1];
for(i=1;i<n+2;i++)
first[i]=-1;
for(i=1;i<m+1;i++){
next[i]=first[u[i]];
first[u[i]]=i;
System.out.println(i+" u,v,w: "+u[i]+" "+v[i]+" "+w[i]);
}
//遍历
int k;
int[] cost=new int[n+1];
int[] d=new int[n+1];
for(i=1;i<n+1;i++){
cost[i]=9999;
d[i]=-1;
}
cost[n]=0;
for(i=n-1;i>0;i--){
k=first[i];
while(k!=-1){
//System.out.println(u[k]+" "+v[k]+" "+w[k]);
if(w[k]+cost[v[k]]<cost[u[k]]){
cost[u[k]]=w[k]+cost[v[k]];
d[u[k]]=v[k];
}
k=next[k];
}
}
i=1;
System.out.println();
System.out.print("1");
while(d[i]!=-1){
System.out.print("->"+d[i]);
d[i]=d[d[i]];
}
System.out.println(" cost[1]:"+cost[1]);
}
}
2)动态规划的向后处理法
package dynamicProgramming;
public class BGRAPH {
public static void main(String[] args) {
// TODO Auto-generated method stub
int i;
int first[],next[];
int n=12;
int m=21;
int[] u={0,1,1,1,1,2,2,2,3,3,4,5,5,6,6,7,7,8,8,9,10,11};
int[] v={0,2,3,4,5,6,7,8,6,7,8,7,8,9,10,9,10,10,11,12,12,12};
int[] w={0,9,7,3,2,4,2,1,2,7,11,11,8,6,5,4,3,5,6,4,2,5};
first=new int[n+1];
next=new int[m+1];
for(i=1;i<n+1;i++)
first[i]=-1;
for(i=1;i<m+1;i++){
next[i]=first[u[i]];
first[u[i]]=i;
System.out.println(i+" u,v,w: "+u[i]+" "+v[i]+" "+w[i]);
}
//遍历
int k;
int[] cost=new int[n+1];
int[] d=new int[n+1];
for(i=1;i<n+1;i++){
cost[i]=9999;
d[i]=-1;
}
cost[1]=0;
for(i=1;i<n+1;i++){
k=first[i];
while(k!=-1){
if(w[k]+cost[u[k]]<cost[v[k]]){
cost[v[k]]=w[k]+cost[u[k]];
d[v[k]]=u[k];
}
k=next[k];
}
}
i=12;
System.out.println();
System.out.print("12");
while(d[i]!=-1){
System.out.print(" <-- "+d[i]);
d[i]=d[d[i]];
}
System.out.println(" cost[1]:"+cost[12]);
}
}