线段树模板

#define maxn 100005
#define mid ((l+r)>>1)
#define lson rt<<1, l, mid
#define rson rt<<1|1, mid+1, r
#define ll long long
int len[maxn<<2], lazy[maxn<<2], sum[maxn<<2], mx[maxn<<2];
int a, b, c, n, m;

void pushup(int rt) {
sum[rt] = sum[rt<<1] + sum[rt<<1|1];
}

void pushdown(int rt){
if(lazy[rt])
{
lazy[rt<<1] = lazy[rt];
lazy[rt<<1|1] = lazy[rt];
sum[rt<<1] =  lazy[rt] * len[rt<<1];
sum[rt<<1|1] = lazy[rt] * len[rt<<1|1];
lazy[rt] = 0;
}
}

void build(int rt, int l, int r){
lazy[rt] = 0;
len[rt] = (r-l+1);
if( l == r) {
        sum[rt] = 1; return;}

build(lson);
build(rson);
pushup(rt);
}

void update(int rt, int l, int r) {
if( a > r || b < l ) return;
if( a <= l && b >= r) /**a l r b*/
{
lazy[rt] = c;
sum[rt] = c * len[rt];
return;
}

pushdown(rt);
update(lson);
update(rson);
pushup(rt);
}

ll query(int rt, int l, int r) {
if( a > r || b < l ) return 0;
if( a <= l && b >= r)
return sum[rt];

pushdown(rt);

ll ans = 0;
ans += query(lson);
ans += query(rson);
return ans;
}

int main() {
int t, ww = 1;
scanf("%d", &t);
while(t--) {
scanf("%d %d", &n,&m);
build(1, 1, n);
while(m--)  {
scanf("%d %d %d", &a, &b, &c);
update(1, 1, n);
//cout << sum[1] << endl;
}
printf("Case %d: The total value of the hook is %d.\n", ww++, sum[1]);
}
}