uva 1374 快速幂计算

#include <iostream>

#include <cstdio>

#include <cmath>

#include <cstring>

#include <algorithm>

#include <cstdlib>

#include <stack>

#include <cctype>

#include <string>

#include <malloc.h>

#include <queue>

#include <map>



using namespace std;



const int INF = 0xffffff;

const double esp = 10e-8;

const double Pi = 4 * atan(1.0);

const int Maxn = 2000+10;

const long long mod =  2147483647;

const int dr[] = {1,0,-1,0,-1,1,-1,1};

const int dc[] = {0,1,0,-1,1,-1,-1,1};

typedef long long LL;



LL gac(LL a,LL b){

    return b?gac(b,a%b):a;

}



int n,ans[Maxn],maxd;

bool vis[Maxn];



int dfs(int step,int s){

    ans[step] = s;

    if(step == maxd){

        if(vis[n])

            return 1;

        return 0;

    }

    if(ans[step] > 2000 || s * 1 << (maxd-step) < n){

        return 0;

    }

    for(int i = 0;i<= step;i++){

        int t = s + ans[i];

        if(!vis[t]){

            vis[t] = 1;

            if(dfs(step+1,t))

                return 1;

            vis[t] = 0;

        }

        t = abs(s-ans[i]);

        if(t > 0 && !vis[t]){

            vis[t] = 1;

            if(dfs(step+1,t))

                return 1;

            vis[t] = 0;

        }

    }

    return 0;

}



int main()

{

#ifndef ONLINE_JUDGE

    freopen("inpt.txt","r",stdin);

#endif

    while(~scanf("%d",&n) && n){



        for(maxd = 0;;maxd++){

            memset(vis,0,sizeof(vis));

            vis[1] = 1;

            if(dfs(0,1)){

                printf("%d\n",maxd);

                break;

            }

        }

    }

    return 0;

}

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