WHAT A PITY!
#include<stdio.h>
int main()
{
int month[13]={0};
int j=0,mom=0,i;
float all;
for(i=1;i<13;i++)
scanf("%d",&month[i]);
for(i=1;i<13;i++)
{
j=300-month[i];
if(j<0)
{
printf("-%d",i);
return 0;
}
mom=j/100*100;
j=j%100;
}
all=mom*1.2+j;
printf("%g",all);
}

#include<iostream>
int main()
{
    int consume[12];
    int store = 0;
    for (int i = 0; i < 12; i++)
    {
        std::cin >> consume[i];
    }
    int amount=0;
    for (int i = 0; i < 12; i++)
    {
        amount =amount+ 300 - consume[i];
        if (amount < 0)
        {
            std::cout <<-1*( i + 1);
            return 0;
        }
        store =store + amount - amount % 100;
        amount %= 100;
    }
    std::cout << store*120/100 + amount;
    return 0;
}

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
int a,ans,Ans;
int main()
{
int i=1;
for(;i<=12;i++)
{
scanf("%d",&a);
Ans+=(ans+300-a)/100*100;
if(ans+300-a<0) {printf("-%d",i);return 0;};
ans=(ans+300-a)%100;
}
if(i==13) printf("%g",ans+Ans*1.2);
return 0;
}

#include<iostream>
using namespace std;
int main()
{
int a[12],b[12];
int s,i,k;
k=0;
s=0;
for(i=0;i<12;i++)
{
cin>>a[i];
s=s+300-a[i];
k=k+s/100;
b[i]=s;
if(s>=100)
{
s%=100;
b[i]=s;
}
}
for(i=0;i<12;i++)
{ if(b[i]<0)
{
cout<<-(i+1)<<endl;
break;
}
if((i==11)&&(b[i]>0))
cout<<(k*120+s)<<endl;
}
return 0;
}

又是浮点数惹的祸。。。乘以1.2要注意了，还是直接除100再乘120吧。。。。
```c++
#include<cstdio>
#include<cstring>
#include<cmath>
int main()
{
int n,yu = 0,a=0;
int sum = 0;
for(int i=1;i <= 12;i++)
{
scanf("%d",&n);
if(yu + 300 - n < 0) {printf("-%d\n",i);a = 1;break;}
if(yu + 300 - n >= 100) {sum += ((300+yu-n)/100)*100;yu = yu +300-n-(((300+yu-n)/100)*100);}
else yu = yu + 300 - n;
// printf("sum = %d yu = %d\n",sum,yu);
}
if(a == 0){printf("%d\n",(sum/100)*120 + yu);}

return 0;
}

#include<stdio.h>
#define N 12

int main()
{
int money[N];
int sum=0,sum1=0;
int x=0,i,n;
for(i=0;i<N;i++)
{
scanf("%d",&money[i]);
}
for(i=0;i<12;i++)
{
x = x+300;
if(x<money[i])
{
printf("-%d",i+1);
return 0;
}
else
{
sum = x - money[i];
n = sum/100;
sum1 = sum1+ n*100;
x = sum - n*100;
}
}

sum1 = sum1*1.2 + x;
printf("%d",sum1);

}

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <map>
#include <vector>
#include <stack>
#include <queue>

using namespace std;

int a,b;

int main(){
for(int i=1;i<=12;i++){
a=a+299+scanf("%d",&a)-a;
if(a<0)return printf("%d\n",-i)&0;
b+=a/100;a%=100;
}
printf("%d\n",a+b*120);
}

#include<iostream>
#include<cstdio>
#include<cstring>
#define N 14
using namespace std;
int tot;
int haisheng[N];
int hua[N];
int main()
{
ios::sync_with_stdio(false);
for(int i=1;i<=12;i++)
cin>>hua[i];
for(int i=1;i<=12;i++)
{
haisheng[i] = 300 + haisheng[i-1]-hua[i];
if(haisheng[i]<0)
{
cout<<"-"<<i<<endl;
return 0;
}
tot += (haisheng[i]/100)*100;
haisheng[i] = haisheng[i]%100;

}

cout<<haisheng[12]+tot*1.2;
return 0;
}

#include <iostream>
using namespace std;
int main()
{
    int a[13],b[13],c[13],sum=0;
    int i,key=0,k;
    b[0]=0;
    c[0]=0;
    for(i=1;i<13;i++)
        cin>>a[i];
    for(i=1;i<13;i++)
    {  
        c[i]=(300-a[i]+b[i-1])/100;//存的钱
        b[i]=(300-a[i]+b[i-1])%100;//留下的钱
        sum+=c[i];
        if(a[i]>300+b[i-1])
        {
            cout<<-(i);
            key=1;
            break;
        }
    }
    if(key==0)
    cout<<sum*120+b[12];//注意要加上12月手上剩的钱,不然会死得很惨!
    return 0;
}

#include<cstdio>
using namespace std;
int main()
{
    int a[13];
    for (int i=1;i<=12;i++) scanf("%d",&a[i]);
    a[0]=0;
    int x=0,f=0;
    for (int i=1;i<=12;i++){
        a[i]=a[i-1]+300-a[i];
        if (a[i]>=0){
            x+=a[i]-(a[i]%100);
            a[i]=a[i]%100;
        }
        else {
            printf("-%d\n",i);
            f=1;break;
        }
    }
    if (!f) printf("%d\n",(x/100)*120+a[12]);
    return 0;
}

#include<iostream>
#include<cstdio>

using namespace std;
int main()
{
    int mother_bank=0;
    int XMmon_banl=0;
    int XMcost;
    int god_month=0;
    cout<<1<<":";
    for(int i=1;i<=12;i++)
    {
        cin>>XMcost;
        XMmon_banl+=300;
        if(XMmon_banl<XMcost&&god_month==0)
        {
            god_month = i;
            XMmon_banl = 0;
            continue;
        }
        XMmon_banl -= XMcost;
        mother_bank += (XMmon_banl/100)*100;
        XMmon_banl %= 100;
        cout<<"母亲: "<<mother_bank;
        cout<<"小明剩余: "<<XMmon_banl<<endl<<endl;
        cout<<i+1<<":";
    }
    if(god_month>0)
        cout<<-god_month<<endl;
    else
    {
        double ans;
        ans = XMmon_banl + mother_bank;
        cout<<"mother's: "<<mother_bank<<endl;
        cout<<"XMmon_banl's: "<<XMmon_banl<<endl;
        ans += 0.2*ans;
        cout<<ans<<endl;
    }
    return 0;
}

/*
290
230
280
200
300
170
140
50
90
80
200
60

*/
1:290
母亲: 0小明剩余: 10

2:230
母亲: 0小明剩余: 80

3:280
母亲: 100小明剩余: 0

4:200
母亲: 200小明剩余: 0

5:300
母亲: 200小明剩余: 0

6:170
母亲: 300小明剩余: 30

7:140
母亲: 400小明剩余: 90

8:50
母亲: 700小明剩余: 40

9:90
母亲: 900小明剩余: 50

10:80
母亲: 1100小明剩余: 70

11:200
母亲: 1200小明剩余: 70

12:60
母亲: 1500小明剩余: 10

13:mother's: 1500
XMmon_banl's: 10
1812

Process returned 0 (0x0) execution time : 1.899 s
Press any key to continue.

#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
int mother_bank=0;
int XMmon_banl=0;
int XMcost;
int god_month=0;
for(int i=1;i<=12;i++)
{
cin>>XMcost;
XMmon_banl+=300;
if(XMmon_banl<XMcost&&god_month==0)
{
god_month = i;
XMmon_banl = 0;
continue;
}
XMmon_banl -= XMcost;
mother_bank += (XMmon_banl/100)*100;
XMmon_banl %= 100;
}
if(god_month>0)
cout<<-god_month<<endl;
else
{
double ans;
ans = XMmon_banl + mother_bank;
cout<<mother_bank<<endl;
cout<<XMmon_banl<<endl;
ans += 0.2*ans;
cout<<ans<<endl;
}
return 0;
}
为啥会娃。。。。它要求加上剩下的钱20%是 :（妈妈存的那整百的钱）*0.2，还是津津小金库的剩下的钱*0.2，还是（妈妈存的那整百的钱 + 津津小金库的剩下的钱）*0.2；

弱爆啊！

var x,i,s,j:longint;
begin
for i:=1 to 12 do
begin
readln(x);
s:=s+300-x;
if s<0 then
begin
writeln('-',i);
halt;
end;
j:=j+s div 100;
s:=s mod 100;
end;
if j>0 then writeln(j*120+s);
end.

#include<cstdio>
#include<iostream>
using namespace std;
int main(){
int i;
int money[13];
for(i=1;i<=12;i++){
cin>>money[i];
}
int now=0,save=0,flag=0;
for(i=1;i<=12;i++){
now=now+300;
if(now<money[i]){
flag=i;
break;
}
int temp=(now-money[i])/100;
save=save+temp*100;
now=now-money[i]-temp*100;
}
if(flag){
cout<<"-"<<flag;
return 0;
}
int left=(save/100)*120+now;//实数直接不能赋给整数
cout<<left;
return 0;
}

小数运算误差
#include <cstdio>

int main(){
#ifdef DEBUG
freopen("in.txt","r",stdin);
#endif
int a[13];
for(int i=1;i<=12;i++)
scanf("%d",&a[i]);
int now=0,save=0,flag=0;
for(int i=1;i<=12;i++){
now+=300;
if(now<a[i]){
flag=i;
break;
}
int temp=(now-a[i])/100;
save+=temp;
now-=100*temp+a[i];
}
if(flag){
printf("-%d",flag);
return 0;
}
save*=120;
printf("%d",save+now);

return 0;
}

发个垃圾题解：
c++
#include<stdio.h>
int m=0,n=0,x;
int main(){
for(int i=0;i<12;++i){
n+=300; scanf("%d",&x);
if(x>n) return 0&printf("-%d",i+1);
m+=(n-x)/100*100; n=(n-x)%100;
}
printf("%d",m/5*6+n);
}


program ssa;
var
a:array[1..15]of integer;
i,n,b,m:integer; c:real;
begin
assign(input,'save.in');
reset(input);
assign(output,'save.out');
rewrite(output);
for i:=1 to 12 do
read(a[i]);
for i:=1 to 12 do
begin
n:=n+300-a[i];
if n>99 then begin m:=(n div 100)*100; b:=b+m; n:=n-m; end;
if n<0 then begin writeln('-',i); break; end;
end;
if n>0 then begin c:=n+b*1.2; writeln(c:0:0) end;
close(input);
close(output);
end.

#include<Stdio.h>
int a[15],b[15],i,c,d=1;
float x=0;
int main()
{
for(i=1;i<=12;i++)
{
scanf("%d",&a[i]);
if(300-a[i]+b[i-1]>=0)
{
if(300-a[i]+b[i-1]>=100)
{
x=x+(((300-a[i]+b[i-1])/100)*100);//x=总钱
b[i]=300-a[i]+b[i-1]-(((300-a[i]+b[i-1])/100)*100);//b是上个月留下的钱
}
else
{
b[i]=300-a[i]+b[i-1];
}
}
else
{
d=-500;
b[14]=i;break;
}
}
x=x*1.2+b[12];
c=x;
if(d==1)
{
printf("%d",c);
}
else if(d==-500)
printf("%d",-b[14]);
return 0;
}
无比丑陋的题解

#include <iostream>

void Proc1();
int main()
{
Proc1();
return 0;
}
void Proc1()
{
using namespace std;
int Mother=0, Month[13] = { 0 }, budget[12];
for (int i = 0; i < 12; i++)
cin >> budget[i];
for (int i = 1; i <= 12; i++)
{

Month[i] = Month[i - 1] + 300;
if (Month[i] < budget[i - 1])
{
cout << '-' << i;
return;
}
Mother += (Month[i] - budget[i - 1])/100 *100;
Month[i] = (Month[i]-budget[i-1]) % 100;
}
cout << Mother / 5 * 6+Month[12] << endl;
}

program ex;
var a:array[1..1000]of longint;
jy,b,n,k,i,j,ans,x:longint;
m:real;
begin
for i:=1 to 12 do
read(a[i]);
for i:=1 to 12 do
begin
a[13]:=300+jy;
if a[13]<a[i] then
begin
x:=-i;
write(-i);
exit;
end;
if a[13]>=a[i] then
begin
ans:=300-a[i]+jy;
jy:=ans mod 100;
n:=n+ans div 100;
end;
end;
m:=n*100*1.2+jy;
if x=0 then
write(m:0:0);
end.