CF272C Dima and Staircase(线段树/贪心)

线段树直接维护区间最大值即可。或者可以发现，最大值只可能出现在最左端或最右端，贪心解决。

线段树

#include <bits/stdc++.h>using namespace std;#define ll long long#define inf 0x3f3f3f3f#define N 100010inline 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,m,a[N];struct node{    ll mx,lazy;}tree[N<<2];inline void pushup(int p){    tree[p].mx=max(tree[p<<1].mx,tree[p<<1|1].mx);}inline void pushdown(int p){    if(!tree[p].lazy) return;    tree[p<<1].lazy=tree[p].lazy;tree[p<<1|1].lazy=tree[p].lazy;    tree[p<<1].mx=tree[p].lazy;tree[p<<1|1].mx=tree[p].lazy;    tree[p].lazy=0;}inline void build(int p,int l,int r){    if(l==r){tree[p].mx=a[l];return;}    int mid=l+r>>1;    build(p<<1,l,mid);build(p<<1|1,mid+1,r);    pushup(p);}ll qmax(int p,int l,int r,int x,int y){    if(x<=l&&r<=y) return tree[p].mx;    int mid=l+r>>1;pushdown(p);ll res=0;    if(x<=mid) res=max(res,qmax(p<<1,l,mid,x,y));    if(y>mid) res=max(res,qmax(p<<1|1,mid+1,r,x,y));    return res;}void update(int p,int l,int r,int x,int y,ll val){    if(x<=l&&r<=y){tree[p].lazy=val;tree[p].mx=val;return;}    int mid=l+r>>1;pushdown(p);    if(x<=mid) update(p<<1,l,mid,x,y,val);    if(y>mid) update(p<<1|1,mid+1,r,x,y,val);    pushup(p);}int main(){//  freopen("a.in","r",stdin);    n=read();    for(int i=1;i<=n;++i) a[i]=read();    build(1,1,n);m=read();    while(m--){        int x=read(),val=read();        ll res=qmax(1,1,n,1,x);        printf("%I64d\n",res);        update(1,1,n,1,x,res+val);    }    return 0;}