HDU 1698 Just a Hook（线段树区间覆盖）

线段树基本操作练习，防手生

#include <cstdio>
#include <cstring>
#include <cstdlib>

#define lson l, m, rt << 1
#define rson m + 1, r, rt << 1 | 1
#define lc rt << 1
#define rc rt << 1 | 1

const int MAXN = 100100;

int sum[MAXN << 2];
int lazy[MAXN << 2];

void PushUp( int rt )
{
    sum[rt] = sum[lc] + sum[rc];
    return;
}

void PushDown( int rt, int m )
{
    if ( lazy[rt] )
    {
        lazy[lc] = lazy[rt];
        lazy[rc] = lazy[rt];

        /*这里注意写法，之前我传进来的是l, r, m
         *sum[lc] = lazy[rt]*( m - l + 1 );
         *sum[rc] = lazy[rt]*( r - m + 1 );
         *然后WA了
         **/
        sum[lc] = lazy[rt]*( m - ( m >> 1 ) );
        sum[rc] = lazy[rt]*( m >> 1 );

        lazy[rt] = 0;
    }
    return;
}

void build( int l, int r, int rt )
{
    lazy[rt] = 0;
    sum[rt] = 1;
    if ( l == r ) return;
    int m = ( l + r ) >> 1;
    build( lson );
    build( rson );
    PushUp(rt);
    return;
}

void Update( int L, int R, int c, int l, int r, int rt )
{
    if ( L <= l && r <= R )
    {
        lazy[rt] = c;
        sum[rt] = c * ( r - l + 1 );
        return;
    }

    int m = ( l + r ) >> 1;
    PushDown( rt, r - l + 1 );
    if ( L <= m ) Update( L, R, c, lson );
    if ( R > m  ) Update( L, R, c, rson );
    PushUp( rt );

    return;
}

int N, Q;

int main()
{
    int T, cas = 0;
    scanf( "%d", &T );
    while ( T-- )
    {
        scanf( "%d", &N );
        build( 1, N, 1 );
        scanf( "%d", &Q );
        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.
", ++cas, sum[1] );
    }
    return 0;
}