E - Replace Digits
You have a string SS of length NN. Initially, all characters in SS are 1s.
You will perform queries QQ times. In the ii-th query, you are given two integers L_i, R_iLi,Ri and a character D_iDi (which is a digit). Then, you must replace all characters from the L_iLi-th to the R_iRi-th (inclusive) with D_iDi.
After each query, read the string SS as a decimal integer, and print its value modulo 998,244,353998,244,353.
Input is given from Standard Input in the following format:
NN QQ L_1L1 R_1R1 D_1D1 :: L_QLQ R_QRQ D_QDQ
Print QQ lines. In the ii-th line print the value of SS after the ii-th query, modulo 998,244,353998,244,353.
Copy
8 5 3 6 2 1 4 7 3 8 3 2 2 2 4 5 1
Copy
11222211 77772211 77333333 72333333 72311333
题意:有一个长为n的串,初始的每个位置都是1
m个操作,每次操作l r x,把l~r这一段位置上的每个数都改成x
每次修改之后看总的串膜上998,244,353之后的结果
思路:先建树
sum表示l~r这段的总数,s表示l~r这段的数应该乘的数位,lazy表示懒标记
建树的时候sum和s随着更新
但是修改的时候只有sum在更新,因为l~r这段应该乘的位数是不变的
#include
using namespace std;
const int N=2e5+10;
const long long mod=998244353;
typedef long long ll;
struct name{int l,r;ll sum,lazy,s;
}tr[N*4];
int n,m;
ll a[N];
void pushup(int u){tr[u].sum =(tr[u<<1].sum+tr[u<<1|1].sum )%mod;tr[u].s =(tr[u<<1].s +tr[u<<1|1].s)%mod;
}
void build(int u,int l,int r){if(l==r){tr[u]={l,r,a[l],0,a[l]};}else{int mid=l+r>>1;tr[u]={l,r,0,0,0};build(u<<1,l,mid);build(u<<1|1,mid+1,r);pushup(u);}
}
void pushdown(int u){if(tr[u].lazy ){tr[u<<1].lazy =tr[u].lazy ;tr[u<<1].sum =tr[u<<1].s *tr[u].lazy %mod;tr[u<<1|1].lazy =tr[u].lazy ;tr[u<<1|1].sum =tr[u<<1|1].s *tr[u].lazy %mod;tr[u].lazy =0; }
}
void modify(int u,int l,int r,ll x){if(l<=tr[u].l &&r>=tr[u].r ){tr[u].lazy =x;tr[u].sum =tr[u].s *x%mod;}else{pushdown(u);int mid=tr[u].l +tr[u].r >>1;if(l<=mid)modify(u<<1,l,r,x);if(r>mid)modify(u<<1|1,l,r,x);tr[u].sum =(tr[u<<1].sum +tr[u<<1|1].sum)%mod; }
}
int main(){scanf("%d%d",&n,&m);a[n]=1;for(int i=n-1;i>=1;i--){a[i]=a[i+1]*10%mod;}build(1,1,n);while(m--){int l,r;ll x;scanf("%d%d%lld",&l,&r,&x);modify(1,l,r,x);printf("%lld\n",tr[1].sum );}return 0;
}
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