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;
}