暑假热身F题

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本文解析了 CodeForces 平台上的题目 1141E，该题描述了一场超级英雄与怪物之间的战斗。通过分析怪物生命值随时间变化的规律，给出了解决方案来确定怪物死亡的具体时间点。

http://codeforces.com/problemset/problem/1141/E
F - Superhero Battle CodeForces - 1141E

       A superhero fights with a monster. The battle consists of rounds, each of which lasts exactly n minutes. After a round ends, the next round starts immediately. This is repeated over and over again.

Each round has the same scenario. It is described by a sequence of n numbers: d1,d2,…,dn (−106≤di≤106). The i-th element means that monster’s hp (hit points) changes by the value di during the i-th minute of each round. Formally, if before the i-th minute of a round the monster’s hp is h, then after the i-th minute it changes to h:=h+di.

The monster’s initial hp is H. It means that before the battle the monster has H hit points. Print the first minute after which the monster dies. The monster dies if its hp is less than or equal to 0. Print -1 if the battle continues infinitely.

Input
The first line contains two integers H and n (1≤H≤1012, 1≤n≤2⋅105). The second line contains the sequence of integers d1,d2,…,dn (−106≤di≤106), where di is the value to change monster’s hp in the i-th minute of a round.

Output
Print -1 if the superhero can’t kill the monster and the battle will last infinitely. Otherwise, print the positive integer k such that k is the first minute after which the monster is dead.

Examples
Input
1000 6
-100 -200 -300 125 77 -4
Output
9
Input
1000000000000 5
-1 0 0 0 0
Output
4999999999996
Input
10 4
-3 -6 5 4
Output
-1
第一排输入怪兽初始生命值和每次循环中的回合数；
第二排输入每个回合怪兽生命值变化；
输出多少回合时怪兽会死（生命值小于等于0
是个数学题
前面WA了两发不想思考了就全加的longlong。。。

#include<stdio.h>
#include<algorithm>
#include<string.h>
using namespace std;
long long n,d[200005];
long long h;
int main()
{
	scanf("%lld%lld",&h,&n);
	long long mi=10000005;
	long long sum=0;
	for(long long i=1;i<=n;i++)
	{
		scanf("%lld",d+i);
		sum+=d[i];
		mi=mi<sum?mi:sum;
	}
	if(h+mi>0&&sum>=0)
	{
		printf("-1\n");
		return 0;
	}
	else if(h+mi<=0)
	{
		long long i;
		for(i=1;i<=n;i++)
		{
			h+=d[i];
			if(h<=0)
			break;
		}
		printf("%lld\n",i);
		return 0;
	}
	else if((h+mi)%(-sum)==0)
	{
		long long cout=(h+mi)/(-sum);
		long long temp=-mi;
		long long i;
		for(i=1;i<=n;i++)
		{
			temp+=d[i];
			if(temp<=0)
			break;
		}
		printf("%lld\n",i+cout*n);
		return 0;
	}
	else 
	{
		long long cout=(h+mi)/(-sum)+1;
		long long temp=h+cout*sum;
		long long i;
		for(i=1;i<=n;i++)
		{
			temp+=d[i];
			if(temp<=0)
			break;
		}
		printf("%lld\n",i+cout*n);
		return 0;
	}
}