http://www.lydsy.com/JudgeOnline/problem.php?id=1537
朴素的转移：dp[i][j]=max(dp[i][j-1],dp[i-1][j])+p[i][j]
树状数组优化
按x排序，离散化y
枚举，排序保证x，树状数组查询y
#include<cstdio> #include<iostream> #include<algorithm> using namespace std; #define N 100001 #define lowbit(x) x&-x int c[N]; struct node { int x,y,p; }e[N]; int tot,has[N]; void read(int &x) { x=0; char c=getchar(); while(!isdigit(c)) c=getchar(); while(isdigit(c)) { x=x*10+c-‘0‘; c=getchar(); } } void change(int x,int y) { while(x<=tot) { c[x]=max(c[x],y); x+=lowbit(x); } } int query(int x) { int mx=0; while(x) { mx=max(mx,c[x]); x-=lowbit(x); } return mx; } bool cmp(node p,node q) { if(p.y!=q.y) return p.y<q.y; return p.x<q.x; } int main() { int n,m,k; read(n); read(m); read(k); for(int i=1;i<=k;++i) { read(e[i].x); read(e[i].y); read(e[i].p); has[i]=e[i].x; } sort(has+1,has+k+1); tot=unique(has+1,has+k+1)-has-1; sort(e+1,e+k+1,cmp); int tmp,pos; int ans=0; for(int i=1;i<=k;++i) { pos=lower_bound(has+1,has+tot+1,e[i].x)-has; tmp=e[i].p+query(pos); ans=max(ans,tmp); change(pos,tmp); } cout<<ans; }