L3-007. 天梯地图
L3-007. 天梯地图
题目链接：https://www.patest.cn/contests/gplt/L3-007
Dijstra
这题是Dijstra的变形，麻烦的是两种最短路的相同距离时的选择条件不同，也就是说要写两个Dijstra函数。很早就写完了代码，不过debug了一星期，最后还是参考他人博客才知道自己错哪了= =(易错点已注释)
代码如下：
1 #include<cstdio> 2 #include<cstring> 3 #include<stack> 4 #define N 505 5 using namespace std; 6 const int INF=0x3f3f3f3f; 7 bool mark[N]; 8 int n,Start,End; 9 int lenmp[N][N]; 10 int timemp[N][N]; 11 int lendis[N]; 12 int timedis[N]; 13 int lenpre[N]; 14 int timepre[N]; 15 void lenDijstra(); 16 void timeDijstra(); 17 int main(void){ 18 /**输入**/ 19 memset(lenpre,-1,sizeof(lenpre)); 20 memset(timepre,-1,sizeof(timepre)); 21 int m; 22 scanf("%d%d",&n,&m); 23 for(int i=0;i<n;++i){ 24 lendis[i]=INF; 25 timedis[i]=INF; 26 for(int j=0;j<n;++j){ 27 lenmp[i][j]=INF; 28 timemp[i][j]=INF; 29 } 30 } 31 while(m--){ 32 int a,b,one,length,time; 33 scanf("%d%d%d%d%d",&a,&b,&one,&length,&time); 34 if(one){ 35 lenmp[a][b]=length; 36 timemp[a][b]=time; 37 }else{ 38 lenmp[a][b]=lenmp[b][a]=length; 39 timemp[a][b]=timemp[b][a]=time; 40 } 41 } 42 scanf("%d%d",&Start,&End); 43 /**数据处理**/ 44 lenDijstra(); 45 timeDijstra(); 46 /**输出**/ 47 int k=End; 48 bool flag=1; 49 stack<int>times; 50 while(k!=Start){ 51 times.push(k); 52 if(timepre[k]!=lenpre[k])flag=0; 53 k=timepre[k]; 54 } 55 if(flag){ 56 printf("Time = %d;",timedis[End]); 57 printf(" Distance = %d:",lendis[End]); 58 printf("% d",Start); 59 while(!times.empty()){ 60 printf(" => %d",times.top()); 61 times.pop(); 62 } 63 printf("\n"); 64 }else{ 65 printf("Time = %d:",timedis[End]); 66 printf("% d",Start); 67 while(!times.empty()){ 68 printf(" => %d",times.top()); 69 times.pop(); 70 } 71 printf("\n"); 72 printf("Distance = %d:",lendis[End]); 73 printf("% d",Start); 74 stack<int>diss; 75 k=End; 76 while(k!=Start){ 77 diss.push(k); 78 k=lenpre[k]; 79 } 80 while(!diss.empty()){ 81 printf(" => %d",diss.top()); 82 diss.pop(); 83 } 84 printf("\n"); 85 } 86 return 0; 87 } 88 void lenDijstra(){ 89 int node[N]; 90 memset(node,0,sizeof(node)); 91 node[Start]=1; 92 93 memset(mark,1,sizeof(mark)); 94 lendis[Start]=0; 95 while(1){ 96 int Min=INF,index; 97 for(int i=0;i<n;++i){ 98 if(mark[i]&&Min>lendis[i]){ 99 Min=lendis[i]; 100 index=i; 101 } 102 } 103 if(Min==INF)break; 104 mark[index]=0; 105 for(int i=0;i<n;++i){ 106 int d=lendis[index]+lenmp[index][i]; 107 if(mark[i]&&lendis[i]>d){ 108 lendis[i]=d; 109 lenpre[i]=index; 110 node[i]=node[index]+1; /*非node[i]++*/ 111 }else if(mark[i]&&lendis[i]==d&&node[index]+1<node[i]){ 112 lenpre[i]=index; 113 node[i]=node[index]+1; 114 } 115 } 116 } 117 } 118 void timeDijstra(){ 119 memset(mark,1,sizeof(mark)); 120 int dis[N]; 121 for(int i=0;i<n;++i) 122 dis[i]=lenmp[Start][i]; 123 timedis[Start]=0; 124 dis[Start]=0; 125 while(1){ 126 int Min=INF,index; 127 for(int i=0;i<n;++i){ 128 if(mark[i]&&Min>timedis[i]){ 129 Min=timedis[i]; 130 index=i; 131 } 132 } 133 if(Min==INF)break; 134 mark[index]=0; 135 for(int i=0;i<n;++i){ 136 int t=timedis[index]+timemp[index][i]; 137 int d=dis[index]+lenmp[index][i]; 138 if(mark[i]&&timedis[i]>t){ 139 dis[i]=d; 140 timedis[i]=t; 141 timepre[i]=index; 142 }else if(mark[i]&&timedis[i]==t&&dis[i]>d){ 143 dis[i]=d; 144 timepre[i]=index; 145 } 146 } 147 } 148 }
