就是细节很多，少了两种情况

#include<bits/stdc++.h>
using namespace std;
int main(){
    int t;
    int h,a,H,A;
    int cnt;
    cin >> t;
    int H1;
    for (int i = 0; i < t;i++){
        cnt = 0;
        cin  >> h >> a >> H >> A;
        H1 = H;
        if (A <= 0 ||H1 <= a){
            cnt = -1;
            cout << cnt << endl;
            continue;
        }
        else if(A==0){
            cout << 0 << endl;
            break;
        }
        else{
            while(H>0&&h>0){
                H -= a;
                if(H<=0){
                    cnt++;
                    H = H1;
                     continue;
                }
                h -= A;
                if(h<=0){
                    break;
                }       
            }    
        }
        cout <<cnt<<endl;
    }     
    return 0;
}