【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。

  1 #include <iostream>

  2 #include <cstdio>

  3 #include <cstring>

  4 using namespace std;

  5

  6 #define MAXN 100005

  7 #define lson l, mid, rt<<1

  8 #define rson mid+1, r, rt<<1|1

  9

 10 int str[MAXN<<2], lstr[MAXN<<2], rstr[MAXN<<2];

 11 int nums[MAXN];

 12

 13 inline int mymax(int a, int b) {

 14     return (a>b) ? a:b;

 15 }

 16

 17 inline int mymin(int a, int b) {

 18     return (a<b) ? a:b;

 19 }

 20

 21 void PushUP(int l, int r, int rt) {

 22     int mid;

 23

 24     str[rt] = mymax(str[rt<<1], str[rt<<1|1]);

 25     lstr[rt] = lstr[rt<<1];

 26     rstr[rt] = rstr[rt<<1|1];

 27

 28     mid = (l+r)>>1;

 29     if (nums[mid] < nums[mid+1]) {

 30         if (lstr[rt] == mid-l+1)

 31             lstr[rt] += lstr[rt<<1|1];

 32         if (rstr[rt] == r-mid)

 33             rstr[rt] += rstr[rt<<1];

 34         str[rt] = mymax(str[rt], lstr[rt<<1|1]+rstr[rt<<1]);

 35     }

 36 }

 37

 38 void build(int l, int r, int rt) {

 39     int mid;

 40     if (l == r) {

 41         str[rt] = lstr[rt] = rstr[rt] = 1;

 42         return ;

 43     }

 44     mid = (l+r)>>1;

 45     build(lson);

 46     build(rson);

 47     PushUP(l, r, rt);

 48 }

 49

 50 void update(int x, int c, int l, int r, int rt) {

 51     int mid;

 52     if (l == r) {

 53         nums[x] = c;

 54         return ;

 55     }

 56     mid = (l+r)>>1;

 57     if (x <= mid)

 58         update(x, c, lson);

 59     else

 60         update(x, c, rson);

 61     PushUP(l, r, rt);

 62 }

 63

 64 int query(int ll, int rr, int l, int r, int rt) {

 65     int mid,  ret = 0;

 66     if (ll<=l && rr>=r)

 67         return str[rt];

 68

 69     mid = (l+r)>>1;

 70     if (ll <= mid)

 71         ret = mymax(ret, query(ll,rr,lson));

 72     if (rr > mid)

 73         ret = mymax(ret, query(ll,rr,rson));

 74

 75     if (ll<=mid && mid<rr && nums[mid]<nums[mid+1]) {

 76         ret = mymax(ret, mymin(mid-ll+1,rstr[rt<<1])+mymin(lstr[rt<<1|1],rr-mid));

 77     }

 78

 79     return ret;

 80 }

 81

 82 void output(int beg, int end) {

 83     int i;

 84     for (i=beg; i<end; ++i)

 85         printf("\t%d: l=%d,s=%d,w=%d\n", i, lstr[i], rstr[i], str[i]);

 86 }

 87

 88 int main() {

 89     int case_n, n, m;

 90     int i, x, y;

 91     char cmd[3];

 92

 93     scanf("%d", &case_n);

 94

 95     while (case_n--) {

 96         scanf("%d %d", &n, &m);

 97         for (i=0; i<n; ++i)

 98             scanf("%d", &nums[i]);

 99         build(0, n-1, 1);

100         while (m--) {

101             scanf("%s %d %d", cmd, &x, &y);

102             if (cmd[0] == ‘Q‘) {

103                 printf("%d\n", query(x,y,0,n-1,1));

104             } else {

105                 update(x, y, 0, n-1, 1);

106             }

107             //output(1, 18);

108         }

109     }

110

111     return 0;

112 }