POJ 3278（Catch That Cow）解题纠错

来源：互联网发布：比特彗星设置知乎编辑：程序博客网时间：2024/06/06 19:21

以下来自http://topic.csdn.net/u/20110324/19/b636ea31-2a8c-4f6e-8ff6-86f1f958e4cf.html

#include <iostream>#include <queue>#include <cstdio>using namespace std;struct node {int value;int sign;int step;};node num[200008];void Init(){for(int i=0;i<200008;i++){num[i].sign=0;num[i].step=0;num[i].value=i;}}int bfs(int sta , int end){if(sta==end){return 0;}queue <node> que;num[sta].sign=1;que.push(num[sta]);while(!que.empty()){int x;node temp;temp=que.front();que.pop();x=temp.value;if(num[x*2].sign==0){num[x*2].step=num[x].step+1;num[x*2].sign=1;if(num[x*2].value==end)return num[x*2].step;que.push(num[x*2]);}if(num[x-1].sign==0){num[x-1].step=num[x].step+1;num[x-1].sign=1;if(num[x-1].value==end)return num[x-1].step;que.push(num[x-1]);}if(num[x+1].sign==0){num[x+1].step=num[x].step+1;num[x+1].sign=1;if(num[x+1].value==end)return num[x+1].step;que.push(num[x+1]);}}}int main(){int n,k;while(scanf("%d%d",&n,&k)!=EOF){if(n>k){int temp=n;n=k;k=temp;}Init();printf("%d/n",bfs(n,k));}return 0;}

要保证下标在允许范围内才能避免runningtime error.以下修改ac:
#include <iostream>#include <queue>#include <cstdio>using namespace std;struct node {int value;int sign;int step;};#define MAXNUM 100001node num[MAXNUM];//node num[200008]; 根据题目条件，100001就够了void Init(){for(int i=0;i<MAXNUM;i++) //for(int i=0;i<200008;i++){num[i].sign=0;num[i].step=0;num[i].value=i;}}int bfs(int sta , int end){ if(sta==end) { return 0; } queue <node> que; num[sta].sign=1; que.push(num[sta]); while(!que.empty()) { int x; node temp; temp=que.front(); que.pop(); x=temp.value; if (x<0) continue; //added if((x*2)<MAXNUM && num[x*2].sign==0)//if(num[x*2].sign==0) { num[x*2].step=num[x].step+1; num[x*2].sign=1; if(num[x*2].value==end) return num[x*2].step; que.push(num[x*2]); } if((x-1) < MAXNUM && num[x-1].sign==0) //if(num[x-1].sign==0) { num[x-1].step=num[x].step+1; num[x-1].sign=1; if(num[x-1].value==end) return num[x-1].step; que.push(num[x-1]); } if((x+1) < MAXNUM && num[x+1].sign==0) //if(num[x+1].sign==0) { num[x+1].step=num[x].step+1; num[x+1].sign=1; if(num[x+1].value==end) return num[x+1].step; que.push(num[x+1]); } } return 0;//added}int main(){int n,k;scanf("%d%d",&n,&k);//while(scanf("%d%d",&n,&k)!=EOF) 只有一组输入，不需while//{//if(n>k) 不需交换//{//int temp=n;//n=k;//k=temp;//}Init();printf("%d/n",bfs(n,k));//}return 0;}