int main()
{
int h, m, n;
while(scanf("%d %d %d", &h, &m, &n)!=EOF)
{
if(h<0) {printf("input error!\n"); continue;}
int x=0; //設置當前爬的高度，初始為0
int c=0; //記錄所需的天數
int flag=1;
if(x==h) {printf("cost days: %d\n", c); continue;}
while(1)
{
c++;
x+=m;
if(x>=h) break;
x-=n;
if(x<=0){flag=0; break;}
}
if(flag)
printf("cost days: %d\n", c);
else
printf("It will never go out!\n");
}
return 0;
}
思路：只要青蛙達到井口，它就出去了，不用再滑下去了。