Comet OJ

后面补的

只做了A题

A题 因自过去而至的残响起舞

简单模拟题 没啥说的

AC代码：

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;

namespace io {
    const int SIZE = 1e7 + 10;
    char inbuff[SIZE];
    char *l, *r;
    inline void init() {
        l = inbuff;
        r = inbuff + fread(inbuff, 1, SIZE, stdin);
    }
    inline char gc() {
        if (l == r) init();
        return (l != r) ? *(l++) : EOF;
    }
    void read(int &x) {
        x = 0; char ch = gc();
        while(!isdigit(ch)) ch = gc();
        while(isdigit(ch)) x = x * 10 + ch - '0', ch = gc();
    }
} using io::read;

int main(){
    ll x;
    cin>>x;
    ll sum[100005];
    memset(sum, 0, sizeof(sum));
    sum[1] = 1;
    sum[2] = 2;
    for (int i = 3; i < 100005; i++)
        sum[i] = sum[i - 1] + sum[i - 1] / 2;
    for (int i = 1; i < 100005; i++){
        if (sum[i] > x){
            cout<<i<<endl;
            break;
        }
    }
    return 0;
}

后面看了题解 sum开105就够了 因为i=104时，ai就已经>1e18了