【题目链接】
【算法】
线段树，注意数据量大，要动态开点
【代码】
#include<bits/stdc++.h> using namespace std; const int MAXN = 10000005; int n,q,l,r,opt,size = 1,root = 1; struct Node { int lc,rc,tag,sum; } Tree[MAXN]; template <typename T> inline void read(T &x) { int f = 1; x = 0; char c = getchar(); for (; !isdigit(c); c = getchar()) { if (c == '-') f = -f; } for (; isdigit(c); c = getchar()) x = (x << 3) + (x << 1) + c - '0'; x *= f; } template <typename T> inline void write(T x) { if (x < 0) { putchar('-'); x = -x; } if (x > 9) write(x/10); putchar(x%10+'0'); } template <typename T> inline void writeln(T x) { write(x); puts(""); } inline void push_up(int root) { Tree[root].sum = Tree[Tree[root].lc].sum + Tree[Tree[root].rc].sum; } inline void push_down(int l,int r,int root) { int mid = (l + r) >> 1; if (Tree[root].tag != -1) { if (!Tree[root].lc) Tree[root].lc = ++size; if (!Tree[root].rc) Tree[root].rc = ++size; Tree[Tree[root].lc].tag = Tree[Tree[root].rc].tag = Tree[root].tag; Tree[Tree[root].lc].sum = Tree[root].tag * (mid - l + 1); Tree[Tree[root].rc].sum = Tree[root].tag * (r - mid); Tree[root].tag = -1; } } inline void modify(int &root,int l,int r,int ql,int qr,int val) { int mid; if (!root) root = ++size; if (l == ql && r == qr) { Tree[root].sum = val * (r - l + 1); Tree[root].tag = val; return; } push_down(l,r,root); mid = (l + r) >> 1; if (mid >= qr) modify(Tree[root].lc,l,mid,ql,qr,val); else if (mid + 1 <= ql) modify(Tree[root].rc,mid+1,r,ql,qr,val); else { modify(Tree[root].lc,l,mid,ql,mid,val); modify(Tree[root].rc,mid+1,r,mid+1,qr,val); } push_up(root); } int main() { read(n); read(q); while (q--) { read(l); read(r); read(opt); if (opt == 1) modify(root,1,n,l,r,1); else modify(root,1,n,l,r,0); writeln(n - Tree[1].sum); } return 0; }