HDU - 1698 Just a Hook (线段树区间修改)
https://cn.vjudge.net/problem/HDU-1698
题意
大小为n的数组,数组元素初始值为1,有q次操作,x,y,z表示从第x到第y所有的元素的值变为z,最后问1到n的和。
分析
区间修改,给每个区间打标记。注意这里是直接把整个区间都变为某个数。
#include <iostream> #include <cstdio> #include <cstdlib> #include <cstring> #include <string> #include <algorithm> #include <cmath> #include <ctime> #include <vector> #include <queue> #include <map> #include <stack> #include <set> #include <bitset> using namespace std; typedef long long ll; typedef unsigned long long ull; #define ms(a, b) memset(a, b, sizeof(a)) #define pb push_back #define mp make_pair #define pii pair<int, int> #define eps 0.0000000001 #define IOS ios::sync_with_stdio(0);cin.tie(0); #define random(a, b) rand()*rand()%(b-a+1)+a #define pi acos(-1) const ll INF = 0x3f3f3f3f3f3f3f3fll; const int inf = 0x3f3f3f3f; const int maxn = 100000 + 10; const int maxm = 200000 + 10; const int mod = 998244353; int n; struct ND{ int l,r; ll sum,lazy; }tree[maxn<<2]; int a[maxn]; void pushup(int rt){ tree[rt].sum=tree[rt<<1].sum+tree[rt<<1|1].sum; } void pushdown(int rt,int len){ if(tree[rt].lazy){ tree[rt<<1].lazy=tree[rt].lazy; tree[rt<<1|1].lazy=tree[rt].lazy; tree[rt<<1].sum=tree[rt].lazy*(len-(len>>1)); tree[rt<<1|1].sum=tree[rt].lazy*(len>>1); tree[rt].lazy=0; } } void build(int rt,int l,int r){ tree[rt].l=l,tree[rt].r=r; tree[rt].lazy=0; if(l==r){ tree[rt].sum=1; return; } int mid=(l+r)>>1; build(rt<<1,l,mid); build(rt<<1|1,mid+1,r); pushup(rt); } void update(int rt,int L,int R,int val){ if(L<=tree[rt].l&&tree[rt].r<=R){ tree[rt].lazy=val; tree[rt].sum=1ll*val*(tree[rt].r-tree[rt].l+1); return; } pushdown(rt,tree[rt].r-tree[rt].l+1); int mid=(tree[rt].l+tree[rt].r)>>1; if(mid>=L) update(rt<<1,L,R,val); if(mid<R) update(rt<<1|1,L,R,val); pushup(rt); } ll query(int rt,int L,int R){ if(L<=tree[rt].l&&tree[rt].r<=R) return tree[rt].sum; pushdown(rt,tree[rt].r-tree[rt].l+1); ll sum=0; int mid=(tree[rt].l+tree[rt].r)>>1; if(mid<R) sum+=query(rt<<1|1,L,R); if(mid>=L) sum+=query(rt<<1,L,R); return sum; } int main() { #ifdef LOCAL freopen("in.txt", "r", stdin); // freopen("output.txt", "w", stdout); #endif int t; int cas=1; scanf("%d",&t); while(t--){ scanf("%d",&n); // for(int i=1;i<=n;i++) a[i]=1; build(1,1,n); int q; scanf("%d",&q); while(q--){ int x,y,z; scanf("%d%d%d",&x,&y,&z); update(1,x,y,z); } printf("Case %d: The total value of the hook is %lld.\n",cas++,query(1,1,n)); } return 0; }