快速幂计算

// by BNU_LZM#include<cstdio>#include<algorithm>using namespace std;const int maxn = 1010;int ans[maxn], n;bool dfs(int d, int maxd){if(ans[d] == n) return true;if(d == maxd) return false;int m = 0;for(int i = 0; i <= d; i++) m = max(m, ans[i]);if((m << (maxd-d)) < n) return false;for(int i = d; i >= 0; i--){ans[d+1] = ans[d]+ans[i];if(dfs(d+1, maxd)) return true;ans[d+1] = ans[d]-ans[i];if(dfs(d+1, maxd)) return true;}return false;}int solve(){if(n == 1) return 0;ans[0] = 1;for(int maxd = 1; ; maxd++){if(dfs(0, maxd)) return maxd;}}int main(){scanf("%d", &n);printf("%d", solve());return 0;}