Technocup 2017 - Elimination Round 1 A题

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吐槽

今天真的是蠢哭了，A题错了2个小时，很强势。主要原因在于我认为这道题不用long long存也可以，但是事实并不是这样的，不用long long中途可能会tle，re，我用了深搜和广搜2种方法去写，但是还是写不出了，第五组错了，赛后数据一看，第五组是一个大数据，我发现了问题，改成long long后过了。留个文章提醒自己。。。

DFS版

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;typedef long long LL;LL S[105], flag, h;void dfs(LL a, LL b){    if(a > b || flag) return ;    if(a == b){        flag = 1;        printf("YES\n%I64d\n", h);        for(int i = 0; i < h; i++){            if(i) printf(" ");            printf("%I64d", S[i]);        }        printf("\n");        return ;    }    S[h++] = 2*a;    dfs(2*a, b);    h--;    S[h++] = 10*a+1;    dfs(10*a+1, b);    h--;}int main(){    LL a, b;    while(scanf("%I64d%I64d", &a, &b) != EOF){        flag = h = 0;        S[h++] = a;        dfs(a, b);        if(!flag) printf("NO\n");    }    return 0;}

BFS 版

#include <queue>#include <cstdio>#include <vector>#include <cstring>#include <iostream>#include <algorithm>using namespace std;typedef long long LL;LL a,b;vector <LL> vec;void bfs(){    priority_queue <LL, vector <LL>, greater<LL> > que;    vec.clear();    que.push(a);    vec.push_back(a);    bool flag = false;    while(!que.empty()){        LL cur = que.top(); que.pop();        if(2*cur < b) que.push(2*cur), vec.push_back(2*cur);        else if(2*cur == b){ que.push(2*cur), vec.push_back(2*cur); flag = true; break;}        if(10*cur+1 < b) que.push(10*cur+1), vec.push_back(10*cur+1);        else if(10*cur+1 == b){ que.push(10*cur+1), vec.push_back(10*cur+1); flag = true; break;}    }    if(flag){        printf("YES\n");        int another[1005], cnt = 0;        int cur = vec.size()-1;        another[cnt++] = b;        while(true){            for(int i = cur-1; i >= 0; i--){                if(vec[i]*2 == vec[cur] || vec[i]*10 + 1 == vec[cur]){                    cur = i;                    another[cnt++] = vec[i];                    break;                }            }            if(!cur) break;        }        printf("%d\n", cnt);        int first = 1;        for(int i = cnt-1; i >= 0; i--)            if(first) printf("%I64d", another[i]), first = 0;            else printf(" %I64d", another[i]);        printf("\n");    }    else printf("NO\n");}int main(){    while(scanf("%I64d%I64d", &a, &b) != EOF){        bfs();    }    return 0;}

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