HDU 1754 I Hate It（基础线段树～）

来源：互联网发布：如何给给淘宝号升级编辑：程序博客网时间：2024/06/10 02:26

#include <cstdio>#include <cstring>#include <iostream>using namespace std;#define lson l, m, rt << 1#define rson m + 1, r, (rt << 1) | 1#define INF 0x3f3f3fint tree[200005 * 8], maxn;void pushup(int rt){    tree[rt] = max(tree[rt << 1], tree[(rt << 1) | 1]);}int Query(int L, int R, int l, int r, int rt){    if (L <= l && r <= R)        return tree[rt];    else    {        int m = (l + r) >> 1;        int ans = maxn;        if (L <= m)        {            ans = max(ans, Query(L, R, lson));        }        if (R > m)        {            ans = max(ans, Query(L, R, rson));        }        return ans;    }}void update(int pos, int val, int l, int r, int rt){    if (l == r)        tree[rt] = val;    else    {        int m = (l + r) >> 1;        if (pos <= m)            update(pos, val, lson);        else            update(pos, val, rson);        pushup(rt);    }}void build(int l, int r, int rt){    if (l == r)    {        scanf("%d", &tree[rt]);        return;    }    else    {        int m = (l + r) >> 1;        build(lson);        build(rson);        pushup(rt);    }}int main(void){    int n, m;    while (~scanf("%d%d", &n, &m))    {        memset(tree, 0, sizeof(tree));        build(1, n, 1);        while (m--)        {            maxn = -INF;            char s[30];            int a, b;            scanf("%s", s);            scanf("%d%d", &a, &b);            if (s[0] == 'U')                update(a, b, 1, n, 1);            if (s[0] == 'Q')                printf("%d\n", Query(a, b, 1, n, 1));        }    }    return 0;}

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