2748: [HAOI2012]音量调节

#include<iostream>#include<cstdio>using namespace std;inline int read(){    int x=0,f=1;char ch=getchar();    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}    return x*f;}int n,bgn,mx,a[51];bool f[51][1001];int main(){    n=read();bgn=read();mx=read();    for(int i=1;i<=n;i++)a[i]=read();    f[0][bgn]=1;    for(int i=1;i<=n;i++)        for(int j=0;j<=mx;j++){            if(j-a[i]>=0&&f[i-1][j-a[i]])f[i][j]=1;            if(j+a[i]<=mx&&f[i-1][j+a[i]])f[i][j]=1;        }    for(int i=mx;i>=0;i--)        if(f[n][i]){printf("%d",i);return 0;}    printf("-1");    return 0;}