//每天整理一点,太多了
https://www.cnblogs.com/TheRoadToTheGold/p/6254255.html#4175712(ORZ)
POJ 3468 板子题 注意下数据范围 (因为int会爆,以后一定好好看题,浪费我10min....)
http://poj.org/problem?id=3468
#include//线段树题目集 #include #include using namespace std; const int maxn = 4e5 + 15; typedef long long ll; typedef struct { ll l,r,sum,f;//sum为区间和,f为懒人标记 }node; node Tree[maxn];//线段树 ll n,q; ll _left,_right,value; void buildTree(int l,int r,int cur) { Tree[cur].l = l; Tree[cur].r = r;//左右区间范围 if(l==r) { scanf("%lld",&Tree[cur].sum); return; } int mid = (l + r) >> 1; buildTree(l,mid,cur*2); buildTree(mid+1,r,cur<<1|1); Tree[cur].sum = Tree[cur<<1].sum + Tree[cur<<1|1].sum; }//建树 void Down(int cur) { Tree[2*cur].f += Tree[cur].f; Tree[2*cur+1].f += Tree[cur].f; Tree[2*cur].sum += (Tree[2*cur].r - Tree[2*cur].l + 1)*Tree[cur].f; Tree[2*cur+1].sum += (Tree[2*cur+1].r - Tree[2*cur+1].l + 1)*Tree[cur].f; Tree[cur].f = 0;//因为已经传下去了,所以清零 }//懒标记下传 ll ans; void ask_interval(int cur) { if(_left<=Tree[cur].l&&Tree[cur].r<=_right) { ans += Tree[cur].sum; return; } if(Tree[cur].f) Down(cur);//下传懒人标记 ll mid = (Tree[cur].l + Tree[cur].r) >> 1;//mid 中间值 if(_left<=mid) ask_interval(cur<<1); if(_right>mid) ask_interval(cur<<1|1); } void change_interval(int cur) { if(_left<=Tree[cur].l&&Tree[cur].r<=_right)//if node 在区间范围内 { Tree[cur].sum += (Tree[cur].r - Tree[cur].l + 1)*value; Tree[cur].f += value; return; } if(Tree[cur].f) Down(cur); ll mid = (Tree[cur].l + Tree[cur].r) >> 1;//mid 中间值 if(_left<=mid) change_interval(cur<<1); if(_right>mid) change_interval(cur<<1|1); Tree[cur].sum = Tree[cur<<1].sum + Tree[cur<<1|1].sum;//(important) 更新完后一定要更新sum的总和值 }//线段树区间修改 int main() { while(scanf("%lld%lld",&n,&q)==2)//写返回值,不然可能会有些很SB的output 超出limit { memset(Tree,0,sizeof(Tree)); buildTree(1,n,1);//1 ~ n为范围,cur 为当前节点 char cmd; while(q--) { ans = 0; getchar(); scanf("%c",&cmd);//区间查询,区间修改 scanf("%lld%lld",&_left,&_right); if(cmd=='Q') { ask_interval(1); cout<
线段树 GSS1(求静态最大连续子段和)
(挺简单的,看代码就好了)
附个题目链接http://codevs.cn/problem/3981/
#include//线段树求GSS1(最长子区间范围) using namespace std;//主要同于解决求每一个区间范围内的最大连续子串 const int maxn = 2e5 + 32; typedef long long i64;//GSS1 1.全在左子树上 2.全在右子树上 3.左右连续区间都存在 template void read(T &x) { x=0; int f=1; char c=getchar(); while(!isdigit(c)) { if(c=='-') f=-1; c=getchar(); } while(isdigit(c)) { x=x*10+c-'0'; c=getchar(); } x*=f; } void out(i64 ans) { if(ans<0) { putchar('-'); ans=-ans;} char s[20]; int len=0; do s[++len]=ans%10+'0'; while(ans/=10); while(len) putchar(s[len--]); putchar('\n'); } struct Node { i64 sum,lmx,rmx,mx;//sum为区间和,lmx最大左连续区间和,rmx最大右连续区间和,mx最大区间连续值 void clear() { sum = lmx = rmx = mx = 0; } }Tree[4*maxn+1]; typedef struct Node nd; void build_Tree(int node,int l,int r) { if(l==r) { read(Tree[node].mx); Tree[node].lmx = Tree[node].rmx = Tree[node].sum = Tree[node].mx; return; } int mid = (l + r) >> 1; build_Tree(node<<1,l,mid); build_Tree(node<<1|1,mid+1,r); Tree[node].mx = max(Tree[node<<1].mx,Tree[node<<1|1].mx); Tree[node].mx = max(Tree[node].mx,Tree[node<<1].rmx + Tree[node<<1|1].lmx); Tree[node].lmx = max(Tree[node<<1].lmx,Tree[node<<1].sum+Tree[node<<1|1].lmx); Tree[node].rmx = max(Tree[node<<1|1].rmx,Tree[node<<1|1].sum + Tree[node<<1].rmx); Tree[node].sum = Tree[node<<1].sum + Tree[node<<1|1].sum; } int n,m,l,r; nd query(int node,int left,int right) { if(l<=left&&right<=r) return Tree[node]; int mid = (left + right) >> 1; if(r<=mid) return query(node<<1,left,mid);//全在左范围区间 if(l>mid) return query(node<<1|1,mid+1,right); //(important) 和求区间和的板子有所不同,因为可能存在1 ~ 7这种线段树中本身不存在的node,因此需要 //在左右区间都有的情况下分离出来,创造新节点并返回 //左右区间都有 nd lchild; lchild.clear(); lchild = query(node<<1,left,mid); nd rchild; rchild.clear(); rchild = query(node<<1|1,mid+1,right); nd parent; parent.clear(); parent.mx = max(lchild.mx,rchild.mx); parent.mx = max(parent.mx,lchild.rmx+rchild.lmx); parent.lmx = max(lchild.lmx,lchild.sum + rchild.lmx); parent.rmx = max(rchild.rmx,rchild.sum + lchild.rmx); parent.sum = lchild.sum + rchild.sum; return parent; } int main() { read(n); build_Tree(1,1,n); read(m); for(int i=0;i!=m;++i) { read(l); read(r); i64 answer = query(1,1,n).mx; out(answer); } }