我每次调用函数时候都会重新定义一次队列，相当于清空队列， 但为什么会wa，我如果定义在外面，每次清空一次队列，就会过
wa
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<set>
#include<map>
#include<vector>
#include<queue>
#include<stack>
#include<string>
#include<cstring>
#include<cmath>

using namespace std;

const int maxn = 1000000;
int road[maxn];
int pr[maxn];

int bfs(int a, int b){
	memset(pr, 0, sizeof(pr));
	memset(road, 0, sizeof(road));
	queue<int>Q;
	Q.push(a);
	road[a] = 1;
	
	while(!Q.empty()){
		int temp = Q.front(); Q.pop();
		
		int xx[3] = {1, -1, temp};
		for(int i = 0; i < 3; i++){
			int dx = temp + xx[i];
			if(road[dx] == false&&dx >= 0&&dx <= 100000){
				pr[dx] = pr[temp] + 1;
				road[dx] = 1;
				Q.push(dx);
			}
			if(dx == b) return pr[dx];
		}
		if(temp == b) return pr[temp];
	}
}

int main()
{
	int a, b;
	while(scanf("%d%d", &a, &b) != EOF){
		//while(!Q.empty()) Q.pop();
		int res = bfs(a, b);
		printf("%d\n", res);
	}		
	return 0;
} 





ac代码
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<set>
#include<map>
#include<vector>
#include<queue>
#include<stack>
#include<string>
#include<cstring>
#include<cmath>

using namespace std;

const int maxn = 1000000;
int road[maxn];
int pr[maxn];
queue<int>Q;
int bfs(int a, int b){
	memset(pr, 0, sizeof(pr));
	memset(road, 0, sizeof(road));
	
	Q.push(a);
	road[a] = 1;
	
	while(!Q.empty()){
		int temp = Q.front(); Q.pop();
		
		int xx[3] = {1, -1, temp};
		for(int i = 0; i < 3; i++){
			int dx = temp + xx[i];
			if(road[dx] == false&&dx >= 0&&dx <= 100000){
				pr[dx] = pr[temp] + 1;
				road[dx] = 1;
				Q.push(dx);
			}
			if(dx == b) return pr[dx];
		}
		if(temp == b) return pr[temp];
	}
}

int main()
{
	int a, b;
	while(scanf("%d%d", &a, &b) != EOF){
		while(!Q.empty()) Q.pop();
		int res = bfs(a, b);
		printf("%d\n", res);
	}		
	return 0;
} 



求解决