HDU 1698 Just a Hook（线段树成段更新）

来源：互联网发布：linux 查看命令的路径编辑：程序博客网时间：2024/06/06 01:54

#include "string"#include "iostream"#include "cstdio"#include "cmath"#include "algorithm"#define INF 0x3f3f3f3f#define INFL 0x3f3f3f3f3f3f3f3fLLusing namespace std;typedef long long LL;const int M=55;#define lson l , m , rt << 1   #define rson m + 1 , r , rt << 1 | 1   const int maxn = 111111;  int h , w , n;  int col[maxn<<2];  int sum[maxn<<2];  void PushUp(int rt) {      sum[rt] = sum[rt<<1] + sum[rt<<1|1];  }  //懒人标记   void PushDown(int rt,int m) {      if (col[rt]) {          col[rt<<1] = col[rt<<1|1] = col[rt];          sum[rt<<1] = (m - (m >> 1)) * col[rt];          sum[rt<<1|1] = (m >> 1) * col[rt];          col[rt] = 0;      }  }  void build(int l,int r,int rt) {      col[rt] = 0;      sum[rt] = 1;      if (l == r) return ;      int m = (l + r) >> 1;      build(lson);      build(rson);      PushUp(rt);  }  void update(int L,int R,int c,int l,int r,int rt) {      if (L <= l && r <= R) {          col[rt] = c;          sum[rt] = c * (r - l + 1);          return ;      }      PushDown(rt , r - l + 1);      int m = (l + r) >> 1;      if (L <= m) update(L , R , c , lson);      if (R > m) update(L , R , c , rson);      PushUp(rt);  }  int main() {      int T , n , m;      scanf("%d",&T);      for (int cas = 1 ; cas <= T ; cas ++) {          scanf("%d%d",&n,&m);          build(1 , n , 1);          while (m --) {              int a , b , c;              scanf("%d%d%d",&a,&b,&c);              update(a , b , c , 1 , n , 1);          }          printf("Case %d: The total value of the hook is %d.\n",cas , sum[1]);      }      return 0;  }

线段树成段更新的应用，需要用到惰性标记，，多开一个数组，以及区分于单点更新不同。。还是挺好理解的。

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