HDOJ 1698 Just a Hook

带 lazy tag 的线段树，维护区间和，含区间修改操作（最后一次询问）。

# include <stdio.h>



# define MAXN (100005 * 4)



char lazy[MAXN];

int sum[MAXN];



void build(int x, int y, int r)

{

    sum[r] = y-x+1;

    lazy[r] = 0;

    if (x == y) return ;

    int mid = (x+y)>>1, ls = r<<1, rs = r<<1|1;

    build(x, mid, ls);

    build(mid+1, y, rs);

}



void update(int r)

{

    sum[r] = sum[r<<1] + sum[r<<1|1];

}



void pushdown(int x, int y, int r)

{

    int ls, rs, mid;

    if (lazy[r])

    {

        ls = r << 1, rs = r << 1 | 1, mid = (x+y)>>1;

        lazy[ls] = lazy[rs] = lazy[r], lazy[r] = 0;

        sum[ls] = lazy[ls]*(mid-x+1);

        sum[rs] = lazy[rs]*(y - mid);

    }

}



void change(int x, int y, int r, int s, int t, int val)

{

    if (s<=x && y<=t)

    {

        sum[r] = val*(y-x+1);

        lazy[r] = val;

        return ;

    }

    pushdown(x, y, r);

    int mid = (x+y)>>1, ls = r<<1, rs = r<<1|1;

    if (s <= mid) change(x, mid, ls, s, t, val);

    if (mid+1<=t) change(mid+1, y, rs, s, t, val);

    update(r);

}



void init(void)

{

    int n, m, x, y, z;

    

    scanf("%d%d", &n, &m);

    build(1, n, 1);

    while (m--)

    {

        scanf("%d%d%d", &x, &y, &z);

        change(1, n, 1, x, y, z);

    }

}



int main()

{

    int T, i;

    

    scanf("%d", &T);

    for (i = 1; i <= T; ++i)

    {

        init();

        printf("Case %d: The total value of the hook is %d.\n", i, sum[1]);

    }

    

    return 0;

}