利用Floyd-Warshall algorithm解決類似shortest path 的問題

Author: XassassinXsaberX

uva/README.md

@@ -35,6 +35,7 @@
 
 ### 圖論
  [[a674]](https://zerojudge.tw/ShowProblem?problemid=a674)[[解答]](https://github.com/XassassinXsaberX/zerojudge/blob/master/uva/a674.c) (Floyd-Warshall algorithm)  
+ [[c128]](https://zerojudge.tw/ShowProblem?problemid=c128)[[解答]](https://github.com/XassassinXsaberX/zerojudge/blob/master/uva/c128.cpp) (Floyd-Warshall algorithm)  
  [[d282]](https://zerojudge.tw/ShowProblem?problemid=d282)[[解答]](https://github.com/XassassinXsaberX/zerojudge/blob/master/uva/d282.c) (shortest path + Floyd-Warshall algorithm)  
  [[d792]](https://zerojudge.tw/ShowProblem?problemid=d792)[[解答]](https://github.com/XassassinXsaberX/zerojudge/blob/master/uva/d792.c) (shortest path + Floyd-Warshall algorithm)  
  [[d793]](https://zerojudge.tw/ShowProblem?problemid=d793)[[解答]](https://github.com/XassassinXsaberX/zerojudge/blob/master/uva/d793.cpp) (shortest path + dijkstra algorithm)  

uva/c128.cpp

@@ -0,0 +1,130 @@
+#include <iostream>
+#include <map>
+#include <stdlib.h> 
+#define INFINITE 100000000
+#define min(a,b) ((a)<(b))?(a):(b)
+
+/*利用Floyd-Warshall algorithm解決類似shortest path 的問題*/
+
+using namespace std;
+void floyd(int**graph,int n);
+
+
+int main()
+{
+	int n,r;
+	map<string,int> MAP;  //用來將字串轉換成數字
+	map<string,int>::iterator iter,iter1,iter2;
+	string city1,city2;
+	int index,index1,index2;
+	int weight;
+	int**graph,*ptr;
+	int i,j,k;
+	int c=1;
+	int ans;
+	
+	while(cin>>n>>r)
+	{
+		if(n==0 && r==0)
+			break;
+		//動態分配二維陣列 
+		graph = new int*[n];
+		for(i=0;i<n;i++)
+			graph[i] = new int[n];
+			
+		//接下來初始化圖型
+		for(i=0;i<n;i++)
+			for(j=0;j<n;j++)
+			{
+				if(i == j)
+					graph[i][j] = 0;
+				else
+					graph[i][j] = -INFINITE;
+			}
+				
+				 
+		index = 0 ;//用來代表每個城市的代號
+		
+		//以下開始建立圖形的權重 
+		for(i=0;i<r;i++)
+		{
+			cin>>city1>>city2>>weight;
+			
+			
+			//尋找city1的編號 
+			iter = MAP.find(city1);
+			if(iter == MAP.end())
+			{
+				index1 = index;                               //代表city1 為標號 index1 
+				MAP.insert(pair<string,int>(city1,index++));  //將city1 與該編號丟到map容器中 
+			}
+			else
+				index1 = iter->second;                        //代表city1 為編號 index1
+				
+			//尋找city2的編號 
+			iter = MAP.find(city2);
+			if(iter == MAP.end())
+			{
+				index2 = index;                               //代表city2 為標號 index12 
+				MAP.insert(pair<string,int>(city2,index++));  //將city2 與該編號丟到map容器中 
+			}
+			else
+				index2 = iter->second;                        //代表city1為編號 index1 
+				
+			graph[index1][index2] = weight;
+			graph[index2][index1] = weight; 
+			
+		} 
+		
+		cin>>city1>>city2; 
+		
+		
+		//尋找city1的編號 
+		iter = MAP.find(city1);
+		index1 = iter->second;                        //代表city1 為編號 index1
+			
+		//尋找city2的編號 
+		iter = MAP.find(city2);
+		index2 = iter->second;                        //代表city2 為編號 index2
+		
+		//利用Floyd-Warshall algorithm解決類似shortest path 的問題
+		floyd(graph,n);
+		
+		cout<<"Scenario #"<<c++<<endl;
+		ans = min(graph[index1][index2],graph[index2][index1]);
+		cout<< ans <<" tons"<<endl;	
+	 
+		
+		
+		//釋放二維陣列空間 
+		for(i=0;i<n;i++)
+			delete [] graph[i];
+		delete [] graph;
+		MAP.clear();
+	}
+	return 0;
+	
+}
+
+
+void floyd(int**graph,int n)
+{
+	int i,j,k;
+	int min_value;	
+	for(k=0;k<n;k++)
+		for(i=0;i<n;i++)
+			for(j=0;j<n;j++)
+			{
+				min_value = min(graph[i][k],graph[k][j]);
+				if(min_value > graph[i][j])
+					graph[i][j] = min_value;
+			}
+}
+
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