区间合并，和hotel那题差不多，只不过在合并区间的时候加和条件，变成左右儿子相连处是否上升，并且，对父亲的更新取得是最大值。
#include <cstdio> #include <cstring> #include <algorithm> #include <climits> #include <string> #include <iostream> #include <map> #include <cstdlib> #include <list> #include <set> #include <queue> #include <stack> #include<math.h> using namespace std; #define lson l,mid,rt<<1 #define rson mid+1,r,rt<<1|1 const int maxn = 111111; int sum[maxn << 2], lsum[maxn << 2], rsum[maxn << 2]; int num[maxn]; void up(int l, int r, int rt) { lsum[rt] = lsum[rt << 1]; rsum[rt] = rsum[rt << 1 | 1]; sum[rt] = max(sum[rt << 1], sum[rt << 1 | 1]); int mid = (l + r) >> 1; int m = r - l + 1; if (num[mid] < num[mid + 1]){ if (lsum[rt] == (m - (m >> 1))) lsum[rt] += lsum[rt << 1 | 1]; if (rsum[rt] == (m >> 1)) rsum[rt] += rsum[rt << 1]; sum[rt] = max(sum[rt], lsum[rt << 1 | 1] + rsum[rt << 1]); } } void build(int l, int r, int rt) { if (l == r){ sum[rt] = lsum[rt] = rsum[rt] = 1; scanf("%d", &num[l]); return; } int mid = (l + r) >> 1; build(lson); build(rson); up(l, r, rt); } void update(int key, int add, int l, int r, int rt) { if (l == r){ num[l] = add; return; } int mid = (l + r) >> 1; if (key <= mid) update(key, add, lson); else update(key, add, rson); up(l, r, rt); } int ask(int L, int R, int l, int r, int rt) { if (L <= l&&r <= R) return sum[rt]; int mid = (l + r) >> 1; int ans = 0; if (L <= mid) ans = max(ans, ask(L, R, lson)); if (R > mid) ans = max(ans, ask(L, R, rson)); if (num[mid] < num[mid + 1]){ int a = min(mid - L + 1, rsum[rt << 1]) + min(R - mid, lsum[rt << 1 | 1]); ans = max(ans, a); } return ans; } int main() { char str[100]; int Icase; int n, m, a, b; scanf("%d", &Icase); while (Icase--){ scanf("%d%d", &n, &m); build(1, n, 1); for (int i = 0; i < m; i++){ scanf("%s%d%d", str, &a, &b); if (str[0] == 'U'){ a++; update(a, b, 1, n, 1); } else{ a++; b++; cout << ask(a, b, 1, n, 1) << endl; } } } return 0; }