Codeforces Round #278 (Div. 2) C. Fight the Monster 二分+枚举

#include <cstdio>
using namespace std;
#define INF 30100
#define max(a, b) (a) > (b) ? (a) : (b)
int hp[2], atk[2], def[2];
int h, a, d;

bool check(int x){
int bound_hp = x / h, rest = x;
bool found = false;
for(int i = 0; i <= bound_hp && !found; ++i){
int bound_atk = rest / a, rest_d = rest, new_hp = hp[0] + i;
for(int j = 0; j <= bound_atk && !found; ++j){
int new_atk = atk[0] + j;
int new_def = def[0] + rest_d / d;
rest_d -= a;
int dec_y = max(0, atk[1] - new_def), dec_m = max(0, new_atk - def[1]);
if(dec_m == 0)
continue;
else if(dec_y == 0)
found = true;
else{
int time = hp[1] % dec_m ? hp[1] / dec_m + 1 : hp[1] / dec_m;
if(dec_y * time < new_hp)
found = true;
}
}
rest -= h;
}
return found;
}

int main(){
scanf("%d %d %d", &hp[0], &atk[0], &def[0]);
scanf("%d %d %d", &hp[1], &atk[1], &def[1]);
scanf("%d %d %d", &h, &a, &d);
int l = 0, r = INF;
while(l < r){
int mid = l + ((r - l) >> 1);
if(check(mid))
r = mid;
else
l = mid + 1;
}
printf("%d\n", l);
return 0;
}