HDU 1754 单点更新 区间求和 zkw线段树 + 递归线段树

HDOJ 1754

线段树裸题，直接上代码。

AC code：

递归线段树：

//lrl's submission#include<cstdio>#include<cstring>#include<algorithm>using namespace std;#define debug 0#define ls  root << 1, l, mid#define rs  root << 1 | 1, mid + 1, r#define M(a, b) memset(a, b, sizeof(a))const int maxn = 200000 + 5;int mx[maxn << 2], n, m, ip = 0;void pushUp(int root){    mx[root] = max(mx[root << 1], mx[root << 1|1]);}void build(int root, int l, int r){    if(l == r){        scanf("%d", &mx[root]);        return;    }    //printf("%d %d\n", l, r);    //ip++;    //if(ip == 6)        //return;    //return;    int mid = (l + r) >> 1;    build(ls);    build(rs);    pushUp(root);}void update(int root, int l, int r, int a, int b){    if(l == r){        if(l == a){            mx[root] = b;        }        return;    }    if(a < l || a > r)        return;    int mid = (l + r) >> 1;    update(ls, a, b);    update(rs, a, b);    pushUp(root);}int query(int root, int l, int r, int a, int b){    if(b < l || a > r)        return 0;    if(a <= l && r <= b)        return mx[root];    int mid = (l + r) >> 1;    return max(query(ls, a, b), query(rs, a, b));}int main(){#if debug    freopen("in.txt", "r", stdin);#endif // debug    char s[5];    int a, b;    while(~scanf("%d%d", &n, &m))    {        //printf("%d %d\n", n, m);        M(mx, 0);        build(1, 1, n);        while(m--)        {            scanf("%s%d%d", s, &a, &b);            //printf("%d %d\n", a, b);            if(s[0] == 'Q'){                printf("%d\n", query(1, 1, n, a, b));            }            else{                update(1, 1, n, a, b);            }        }    }    return 0;}

写宏的时候， 括号一定要注意， 刚开始mid用宏写没套括号。。。。

zkw线段树， 简单多了：

//lrl's submission#include<cstdio>#include<cstring>#include<algorithm>using namespace std;#define debug 0#define mid (l + r) >> 1#define ls  root << 1, l, mid#define rs  root << 1 | 1, mid + 1, r#define M(a, b) memset(a, b, sizeof(a))const int maxn = 200000 + 5;int mx[maxn << 2], n, m, M;void build(){    for(M = 1; M <= n + 1; M <<= 1);    for(int i = M + 1; i <= M + n; i++){        scanf("%d", &mx[i]);    }    for(int i = M - 1; i >= 1; i--)        mx[i] = max(mx[i << 1], mx[i << 1|1]);}void update(int a, int b){    for(mx[a += M] = b, a >>= 1; a; a >>= 1)        mx[a] = max(mx[a << 1], mx[a << 1|1]);}int query(int a, int b){    a += M - 1;    b += M + 1;    int ans = 0;    while(b - a > 1){        if(a % 2 == 0){            ans = max(ans, mx[a + 1]);        }        if(b % 2)            ans = max(ans, mx[b - 1]);        a >>= 1;        b >>= 1;     }     return ans;}int main(){#if debug    freopen("in.txt", "r", stdin);#endif // debug    char s[5];    int a, b;    while(~scanf("%d%d", &n, &m))    {        //printf("%d %d\n", n, m);        M(mx, 0);        build();        while(m--)        {            scanf("%s%d%d", s, &a, &b);            //printf("%d %d\n", a, b);            if(s[0] == 'Q'){                printf("%d\n", query(a, b));            }            else{                update(a, b);            }        }    }    return 0;}