/*
贪心 负数一定不取
枚举最高位是1 且答案取为0的 位置， 更新答案。
*/
#include<iostream>
#include<cstdio>
#include<cstring>
#define ll long long
#define N 100010
using namespace std;
int n;
ll a[N],ans,sum[N];
char s[N];
ll read()
{
ll x=0,f=1;char c=getchar();
while(c>‘9‘||c<‘0‘){if(c==‘-‘)f=-1;c=getchar();}
while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘;c=getchar();}
return x*f;
}
int main()
{
freopen("maximum.in","r",stdin);
freopen("maximum.out","w",stdout);
scanf("%d",&n);
for(int i=1; i<=n; i++)
{
a[i]=read();
sum[i]=sum[i-1];
if(a[i]>0)sum[i]=sum[i-1]+a[i];
}
scanf("%s",s+1);
ll c=0;
for(int i=n; i>=1; i--)
if(s[i]==‘1‘)
{
ans=max(ans,c+sum[i-1]);
c+=max(a[i],0LL);
}
ans=max(ans,c);
printf("%I64d\n",ans);
return 0;
}
/*
15暴力
*/
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define N 1010
using namespace std;
int n,k;
int l,r,mid;
int num[N],tmp[N];
int ans;
int minn(int a,int b,int i)
{
if(a<b) return tmp[i-1];
else return tmp[i-1]+mid;
}
bool check()
{
int sum=0;
for(int i=1; i<=n; i++) tmp[i]=num[i];
for(int i=2; i<=n; i++)
if(abs(tmp[i]-tmp[i-1])>mid)
{
if(tmp[i+1]>tmp[i]) tmp[i]=max(tmp[i],tmp[i-1]+mid);
else tmp[i]=minn(abs(tmp[i-1]-tmp[i+1]),tmp[i-1]+mid-tmp[i+1],i);
sum++;
}
if(sum>k) return false;
else return true;
}
int main()
{
scanf("%d%d",&n,&k);
for(int i=1; i<=n; i++) scanf("%d",&num[i]);
l=0;
r=1000000000;
while(l<=r)
{
mid=(l+r)/2;
if(check()) ans=mid,r=mid-1;
else l=mid+1;
}
printf("%d",ans);
}
不会分块
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cstdlib>
#include <ctime>
using namespace std;
const int maxn = 200000;
const int len = 400;
int n, A, B,m;
int a[maxn],b[maxn],l[maxn],r[maxn],lb[maxn],tot;
int answer[300][300];
int rt[300][maxn], lt[300][maxn],d[maxn];
//int root[maxn*len], ll[maxn*len], rr[maxn*len],data[maxn*len];
int find(int x)
{
for (int l = 0, r = m; l < r;)
{
int mid = (l + r) / 2;
if (b[mid] == x) return mid;
if (b[mid]>x) r = mid;
else l = mid + 1;
}
return -1;
}
/*int build(int l, int r)
{
if (l == r)
{
tot++;
ll[tot] = rr[tot] = 0;
data[tot] = d[l];
return tot;
}
tot++;
int tmp = tot;
ll[tmp] = build(l, (l + r) / 2);
rr[tmp] = build((l + r) / 2 + 1, r);
data[tmp] = min(data[ll[tmp]], data[rr[tmp]]);
return tmp;
}
int change(int i, int l, int r,int x)
{
if (l == x && r == x)
{
tot++;
ll[tot] = rr[tot] = 0;
data[tot] = n + 1;
return tot;
}
tot++;
int tmp = tot;
ll[tot] = ll[i];
rr[tot] = rr[i];
if (l <= x && x <= (l + r) / 2) ll[tmp] = change(ll[i], l, (l + r) / 2, x);
else rr[tmp] = change(rr[i], (l + r) / 2 + 1, r, x);
data[tmp] = min(data[ll[tmp]], data[rr[tmp]]);
return tmp;
}
int check(int i, int l, int r, int x, int &ans)
{
if (l > x) return 0;
if (1 <= l && r <= x)
{
ans = min(ans, data[i]); return 0;
}
check(ll[i], l, (l + r) / 2, x, ans);
check(rr[i], (l + r) / 2 + 1, r, x, ans);
return 0;
}*/
int main()
{
double ti = clock();
freopen("sequence.in", "r", stdin);
freopen("sequence.out", "w", stdout);
scanf("%d%d%d", &n, &A, &B);
a[0] = 0;
for (int i = 1; i <= n; i++)
{
char c;
for (scanf(" %c", &c); c != ‘A‘ && c != ‘B‘; scanf(" %c", &c));
if (c == ‘A‘) a[i] = a[i - 1] + B;
else a[i] = a[i - 1] - A;
}
for (int i = 0; i <= n; i++) b[i] = a[i];
sort(b, b + n + 1);
m = unique(b, b + n + 1) - b;
for (int i = 0; i <= n; i++)
{
a[i] = find(a[i]);
if (a[i] == -1)
{
printf("???\n");
return 0;
}
}
n++;
int k = n / len;
for (int i = 0; i <= k; i++)
{
int ans = 0;
tot++;
for (int j = i*len; j < n; j++)
{
if (j%len == 0)
{
answer[i][j / len] = ans;
}
if (lb[a[j]] != tot)
{
lb[a[j]] = tot;
l[a[j]] = j;
}
ans = max(ans, j - l[a[j]]);
}
}
for (int i = 0; i < n; i++) r[i] = -1;
for (int i = 0; i < n; i++)
{
r[a[i]] = i;
if (i%len == len - 1)
{
int tmp = i / len;
for (int j = 0; j < n; j++)
rt[tmp][j] = r[j];
}
}
for (int i = 0; i < n; i++) l[i] = -1;
for (int i = n - 1; i >= 0; i--)
{
l[a[i]] = i;
if (i%len == 0)
{
int tmp = i / len;
for (int j = 0; j < n; j++)
lt[tmp][j] = l[j];
}
}
int q;
scanf("%d", &q);
int ans = 0;
for (; q; q--)
{
int L, R;
scanf("%d%d", &L, &R);
L--;
int kl = L / len, kr = R / len;
ans = 0;
if (kl == kr)
{
tot++;
for (int i = L; i <= R; i++)
{
if (lb[a[i]] != tot)
{
lb[a[i]] = tot;
l[a[i]] = i;
}
ans = max(ans, i - l[a[i]]);
}
}
else
{
ans = answer[kl + 1][kr];
tot++;
int tmp = min(n, (kl + 1)*len);
for (int i = L; i < tmp; i++)
{
if (lb[a[i]] != tot)
{
lb[a[i]] = tot;
l[a[i]] = i;
ans = max(ans, rt[kr - 1][a[i]] - i);
}
}
tmp = min(R + 1, n);
for (int i = kr*len; i < tmp; i++)
{
if (lb[a[i]] != tot)
{
if (lt[kl + 1][a[i]] != -1) ans = max(ans, i - lt[kl + 1][a[i]]);
}
else ans = max(ans, i - l[a[i]]);
}
}
printf("%d\n", ans);
}
/*int q;
for (scanf("%d", &q); q; q--)
{
// if (q % 5000 == 0) cerr << q << endl;
int L, R;
tot++;
scanf("%d%d", &L, &R);
int ans = 0;
for (int i = L - 1; i <= R; i++)
{
if (lb[a[i]] != tot)
{
lb[a[i]] = tot;
l[a[i]] = i;
}
ans = max(ans, i - l[a[i]]);
}
printf("%d\n", ans);
}*/
/*for (int i = 0; i <= n; i++)
{
if (lb[a[i]] == 0)
{
lb[a[i]] = 1;
l[a[i]] = i;
d[i] = n + 1;
}
else
{
r[l[a[i]]] = i;
d[i] = i - l[a[i]];
l[a[i]] = i;
}
}
root[0] = build(1, n);
for (int i = 1; i <= n; i++)
{
if (r[i-1] != 0) root[i] = change(root[i - 1], 1, n, r[i-1]);
else root[i] = root[i - 1];
}
int q;
for (scanf("%d", &q); q; q--)
{
int L, R;
scanf("%d%d", &L, &R);
L--;
int ans = n + 1;
check(root[L], 1, n, R, ans);
if (ans == n + 1) printf("-1\n"); else printf("%d\n", ans);
}*/
/* int q;
int tans = 0;
for (scanf("%d", &q); q; q--)
{
int L, R;
scanf("%d%d", &L, &R);
L--;
tot++;
int ans = n + 1;
for (int i = L; i <= R; i++)
{
if (lb[a[i]] != tot)
{
lb[a[i]] = tot;
l[a[i]] = i;
}
else
{
ans = min(ans, i - l[a[i]]);
l[a[i]] = i;
}
}
if (ans == n + 1) printf("-1\n"); else {
printf("%d\n", ans);
tans = max(tans, ans);
}
}
cerr << clock()-ti << " "<<tans<<" "<<A<<" "<<B<<endl;*/
return 0;
}
std
时间： 2024-11-12 15:29:25