线段树 成段更新 hdu1698

#include <iostream>
#include <cstdio>
using namespace std;

#define N 100005

int sum[N << 2], col[N << 2];

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

void pushDown(int rt, int len)
{
    col[rt << 1] = col[rt << 1 | 1] = col[rt];
    sum[rt << 1] = col[rt] * (len - (len >> 1));
    sum[rt << 1 | 1] = col[rt] * (len >> 1);
    col[rt] = 0;
}

void build(int l, int r, int rt)
{
    col[rt] = 0;
    if (l == r) {
       sum[rt] = 1; return;
    }
    int m = (l + r) >> 1;
    build (l, m, rt << 1);
    build (m + 1, r, rt << 1 | 1);
    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;
    }
    if (col[rt]) pushDown (rt, r - l + 1);
    int m = (l + r) >> 1;
    if (m >= L) update (L, R, c, l, m, rt << 1);
    if (m < R) update (L, R, c, m + 1, r, rt << 1 | 1);
    pushUp (rt);
}

int main()
{
    int T, n, q;

    scanf ("%d", &T);
    for (int t = 1; t <= T; t++)
    {
        scanf ("%d\n%d", &n, &q);
        build (1, n, 1);
        while (q--)
        {
            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", t, sum[1]);
    }
    return 0;
}