Segment Tree (interval max query and point modification)--I. Hate It (HDU 1754)

Topic Links:
http://acm.hdu.edu.cn/showproblem.php?pid=1754

Analysis && solving: Direct set template, you need to be aware of the C input. (t^t,c++ input Direct T Super 3000,c input Instant 800+, non-human)

1. Segment Tree Standard preprocessing:

#define LC (D<<1)
#define RC (d<<1|1)
#define MID (L+r >>1)

2. Achievements:

const int Max = 200005;
int A[max];
struct Tr
{
    int mx;
} TR[MAX*3];
void Push (int root)
{
    tr[root].mx = max (tr[lc].mx, tr[rc].mx);
}
void build (int root, int l, int r)
{
    if (L = = r)//gets to the bottom child node
    {
        tr[root].mx = a[l]; Assigns a value directly from the array
        retur n;
    }
    Build (LC, L, mid);
    Build (RC, mid+1, R);
    Push (root);
}

2. Query Maximum value:

int query (int root,  int L,  int r,  int L,  int R)//l,r indicates the query interval
{
    if (l==l && r = = r)
    {
  return tr[root].mx;
    }

    if (R <= mid)
        return query (LC, L, Mid, L, R);
    else if (L > Mid)
        return query (RC, mid+1, R, L, R);
    else
        return max (query (LC, L, Mid, L, mid), query (RC, mid+1, R, Mid+1, R));
}

3. Point modification:

void update (int root,  int L,  int r,  int loc,  int value)
{
    if (L = = r)
    {
        tr[d]. mx = value;
        return;
    }
    if (Loc <= mid) Update (LC, L, Mid, Loc, k);
    else  update (RC, mid+1, R, loc, K);
    Push (root);
}

AC Code:

#include <iostream> #include <cstdio> #include <cstring> #include <algorithm> using namespace St

D

#define LC (D&LT;&LT;1) #define RC (d<<1|1) #define MID (L+r >>1) const int Max = 200005;

int A[max]; struct Tr {int mx;}

TR[MAX*3];

void Push (int d) {tr[d].mx = max (tr[lc].mx, tr[rc].mx);}
        void build (int d, int l, int r) {if (L = = r) {tr[d].mx = a[l];
    return;
    } build (LC, L, mid);
    Build (RC, mid+1, R);
Push (d); } int query (int d, int l, int r, int l, int r) {if (l==l && r = r) {//cout << ":" &
        Lt;<d <<endl;
    return tr[d].mx;
    } if (R <= mid) return query (LC, L, Mid, L, R);
    else if (L > Mid) return query (RC, mid+1, R, L, R);
else return Max (query (LC, L, Mid, L, mid), query (RC, mid+1, R, Mid+1, R)); } void Update (int d, int l, int r, int loc, int k) {if (L = = r) {TR[D].Mx = k;
    return;
    } if (Loc <= mid) Update (LC, L, Mid, Loc, k);
    else update (RC, mid+1, R, loc, K);
Push (d);
    } int main () {int n,m;
        while (~SCANF ("%d%d", &n,&m)) {memset (tr, 0, sizeof (TR));
        for (int i=1;i<=n;i++) {scanf ("%d", &a[i]);
        } build (1, 1, N);
        Char c[2];
            while (m--) {int A, B;
            scanf ("%s%d%d", c,&a,&b);
            if (c[0]== ' U ') update (1,1,N,A,B);
        if (c[0]== ' Q ') printf ("%d\n", Query (1,1,n,a,b));
 }
    }
}