UVALive - 3621 Power Calculus

来源：互联网发布：济南java培训编辑：程序博客网时间：2024/06/06 05:34

题意：给出x和正整数n，问最少需要几次乘除法可以得到x^n

思路：迭代搜索+减枝

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int MAXN = 1010;const int INF = 10000007;int arr[MAXN],num;int dfs(int n,int step){    if (num > step)        return 0;    if (arr[num] == n)        return 1;    if (arr[num] << (step-num) < n)        return false;    for (int i = 0; i <= num; i++){        num++;        arr[num] = arr[num-1] + arr[i];        if (arr[num] <= 10000 && dfs(n,step))            return true;        arr[num] = arr[num-1] - arr[i];        if (arr[num] > 0 && dfs(n,step))            return 1;        num--;    }    return 0;}int main(){    int n;    while (scanf("%d",&n) != EOF && n){        int i;        for (i = 0; ; i++){            arr[num = 0] = 1;            if (dfs(n,i))                break;        }        printf("%d\n",i);    }        return 0;}

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