題目
incoming group has one more member than previous
n members stays for n days
Input: S (1~1000, initial size of the group), D (1~10^15, find D-th day group size)
Example: 1 2 2 3 3 3 4 4 4 4 5 5 5 5 5
解法一：數學公式
1 + 2 + 3 + … + n = n * (n + 1) / 2
#include <iostream>
#define ll long long
using namespace std;
int main(){
int S;
ll D;
while(cin >> S >> D){
ll n = 1;
while((n*(n+1)/2) - ((S-1)*S/2) < D){
n++;
}
cout << n << '\n';
}
}解法二：模擬
#include <iostream>
#define ll long long
using namespace std;
int main(){
int S;
ll D;
while(cin >> S >> D){
int now = S;
while(D > 0){
D -= now;
if(D > 0) now++;
}
cout << now << '\n';
}
}👉 回到：【CPE大學程式能力檢定】目錄
