【HDOJ】3308 LCIS

线段树，题目感觉比较难，看别人思路做的。还得继续练这个专题。

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

 #define MAXN 100005
 #define lson l, mid, rt<<1
 #define rson mid+1, r, rt<<1|1

 int str[MAXN<<], lstr[MAXN<<], rstr[MAXN<<];
 int nums[MAXN];

 inline int mymax(int a, int b) {
     return (a>b) ? a:b;
 }

 inline int mymin(int a, int b) {
     return (a<b) ? a:b;
 }

 void PushUP(int l, int r, int rt) {
     int mid;

     str[rt] = mymax(str[rt<<], str[rt<<|]);
     lstr[rt] = lstr[rt<<];
     rstr[rt] = rstr[rt<<|];

     mid = (l+r)>>;
     if (nums[mid] < nums[mid+]) {
         if (lstr[rt] == mid-l+)
             lstr[rt] += lstr[rt<<|];
         if (rstr[rt] == r-mid)
             rstr[rt] += rstr[rt<<];
         str[rt] = mymax(str[rt], lstr[rt<<|]+rstr[rt<<]);
     }
 }

 void build(int l, int r, int rt) {
     int mid;
     if (l == r) {
         str[rt] = lstr[rt] = rstr[rt] = ;
         return ;
     }
     mid = (l+r)>>;
     build(lson);
     build(rson);
     PushUP(l, r, rt);
 }

 void update(int x, int c, int l, int r, int rt) {
     int mid;
     if (l == r) {
         nums[x] = c;
         return ;
     }
     mid = (l+r)>>;
     if (x <= mid)
         update(x, c, lson);
     else
         update(x, c, rson);
     PushUP(l, r, rt);
 }

 int query(int ll, int rr, int l, int r, int rt) {
     int mid,  ret = ;
     if (ll<=l && rr>=r)
         return str[rt];

     mid = (l+r)>>;
     if (ll <= mid)
         ret = mymax(ret, query(ll,rr,lson));
     if (rr > mid)
         ret = mymax(ret, query(ll,rr,rson));

     if (ll<=mid && mid<rr && nums[mid]<nums[mid+]) {
         ret = mymax(ret, mymin(mid-ll+,rstr[rt<<])+mymin(lstr[rt<<|],rr-mid));
     }

     return ret;
 }

 void output(int beg, int end) {
     int i;
     for (i=beg; i<end; ++i)
         printf("\t%d: l=%d,s=%d,w=%d\n", i, lstr[i], rstr[i], str[i]);
 }

 int main() {
     int case_n, n, m;
     int i, x, y;
     char cmd[];

     scanf("%d", &case_n);

     while (case_n--) {
         scanf("%d %d", &n, &m);
         for (i=; i<n; ++i)
             scanf("%d", &nums[i]);
         build(, n-, );
         while (m--) {
             scanf("%s %d %d", cmd, &x, &y);
             if (cmd[] == 'Q') {
                 printf("%d\n", query(x,y,,n-,));
             } else {
                 update(x, y, , n-, );
             }
             //output(1, 18);
         }
     }

     return ;
 }