拿到題的時候感覺可以用樹狀數組做,因爲查詢是單點的,然後可以對區間進行修改。然後後來發現如果對一個點修改兩次樹狀數組沒法實現(也許是我太渣),因爲是直接覆蓋而不是疊加的。所以最後還是用線段樹寫的。。好久才寫完。。線段樹用的實在是太差了。。。慢慢來吧。。
代碼如下
#include <iostream>
#include <cstdio>
#include <cstring>
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
using namespace std;
const int maxn = 100005;
const int INF = 1e9;
int sum[maxn<<2],lazy[maxn<<2];
int a[maxn],b[maxn];
int op,x,y,k;
void pushup(int rt){
sum[rt] = sum[rt<<1]+sum[rt<<1|1];
}
void pushdown(int rt,int m){
if(lazy[rt]!=INF){
lazy[rt<<1] = lazy[rt<<1|1] = lazy[rt];
sum[rt<<1] = (m-(m>>1))*lazy[rt];
sum[rt<<1|1] = (m>>1)*lazy[rt];
lazy[rt] =INF;
}
}
void build(int l,int r,int rt){
sum[rt] = 0;
lazy[rt] = INF;
if(l == r)return;
int m = (l+r)>>1;
build(lson);
build(rson);
pushup(rt);
}
void update(int L,int R,int c,int l,int r,int rt){
if(L<=l&&r<=R){
sum[rt] = (r-l+1)*c;
lazy[rt] = c;
return ;
}
pushdown(rt,r-l+1);
int m = (l+r)>>1;
if(L<=m)update(L,R,c,lson);
if(R>m)update(L,R,c,rson);
pushup(rt);
}
int query(int aim,int l,int r,int rt){
if(l == r){
//cout<<"lazy "<<lazy[rt]<<endl;
if(lazy[rt]!=INF)return a[sum[rt]+aim];
else return b[sum[rt]+aim];
}
pushdown(rt,r-l+1);
int m = (l+r)>>1;
if(aim<=m)return query(aim,lson);
if(aim>m)return query(aim,rson);
}
int n,m;
int main()
{
while(scanf("%d%d",&n,&m)==2){
memset(sum,0,sizeof(sum));
for(int i=1;i<=n;i++)scanf("%d",&a[i]);
for(int i=1;i<=n;i++)scanf("%d",&b[i]);
build(1,n,1);
while(m--){
scanf("%d%d",&op,&x);
if(op == 1){
scanf("%d%d",&y,&k);
int cg = x-y;
update(y,y+k-1,cg,1,n,1);
}
else {
int ans = query(x,1,n,1);
printf("%d\n",ans);
}
}
}
return 0;
}