Codeforces Round #381 (Div. 1) C

题意：

Alyona造了n座塔。。。。现在要进行m此操作，每次是将[l,r]的塔的高度增加d，

询问每次操作后最长的山峰长度是多少。。

山峰定义为。。。[l,r]内的数，满足al < al+1 < al+2 < .. < amid > .. > ar-2 > ar-1 > ar

长度就是r - l + 1了

solution：

首先对原数列差分，ai = ai+1 - ai

这样山峰就是[l,r]内的数，前面的大于0，后面的小于0，然后长度再+1

这样修改不超过两个数

线段树维护前缀后缀。。。

定义L[o][0]:点o维护的区间内左起最长与左开头数字同号的长度

L[o][1]:点o维护的区间内左起最长与左开头数字先同号后异号的长度

转移写得有点长= =

#include<iostream>#include<cstdio>#include<algorithm>#include<cmath>#include<cstring>#include<vector>#include<queue>#include<set>#include<map>#include<stack>#include<bitset>#include<ext/pb_ds/priority_queue.hpp>using namespace std;const int maxn = 3E5 + 30;const int T = 4;typedef long long LL;int n,m,Max[maxn*T],L[maxn*T][2],R[maxn*T][2];LL a[maxn],A[maxn],va[maxn*T][2];int Judge(LL x) {return x > 0?1:x < 0?-1:0;}void maintain(int o,int l,int r){int lc = (o<<1),rc = (o<<1|1),mid = (l + r) >> 1,tot = 0;Max[o] = max(Max[lc],Max[rc]);if (Judge(va[lc][1])*Judge(va[rc][0]) > 0){if (va[lc][1] > 0) tot = R[lc][0] + L[rc][1];else tot = R[lc][1] + L[rc][0];Max[o] = max(Max[o],tot);}else if (va[lc][1] > 0 && va[rc][0] < 0){tot = R[lc][0] + L[rc][0];Max[o] = max(Max[o],tot);}if (L[lc][0] == mid - l + 1){if (Judge(va[lc][1])*Judge(va[rc][0]) > 0){L[o][0] = L[lc][0] + L[rc][0];L[o][1] = L[lc][0] + L[rc][1];}else if (va[lc][1] != 0 && va[rc][0] != 0){L[o][0] = L[lc][0];L[o][1] = L[lc][0] + L[rc][0];}else L[o][0] = L[lc][0],L[o][1] = L[lc][1];}else if (L[lc][1] == mid - l + 1){L[o][0] = L[lc][0];if (Judge(va[lc][1])*Judge(va[rc][0]) > 0)L[o][1] = L[lc][1] + L[rc][0];else L[o][1] = L[lc][1];}else{L[o][0] = L[lc][0];L[o][1] = L[lc][1];}if (R[rc][0] == r - mid){if (Judge(va[lc][1])*Judge(va[rc][0]) > 0){R[o][0] = R[rc][0] + R[lc][0];R[o][1] = R[rc][0] + R[lc][1];}else if (va[lc][1] != 0 && va[rc][0] != 0){R[o][0] = R[rc][0];R[o][1] = R[rc][0] + R[lc][0];}else R[o][0] = R[rc][0],R[o][1] = R[rc][1];}else if (R[rc][1] == r - mid){R[o][0] = R[rc][0];if (Judge(va[lc][1])*Judge(va[rc][0]) > 0)R[o][1] = R[rc][1] + R[lc][0];else R[o][1] = R[rc][1];}else{R[o][0] = R[rc][0];R[o][1] = R[rc][1];}va[o][0] = va[lc][0];va[o][1] = va[rc][1];}void Modify(int o,int l,int r,int pos,LL x){if (l == r){A[l] += x; Max[o] = 1;va[o][0] = va[o][1] = A[l];L[o][0] = L[o][1] = 1;R[o][0] = R[o][1] = 1;return;}int mid = (l + r) >> 1;if (pos <= mid) Modify(o<<1,l,mid,pos,x);else Modify(o<<1|1,mid+1,r,pos,x);maintain(o,l,r);}int main(){#ifdef DMCfreopen("DMC.txt","r",stdin);#endifcin >> n;for (int i = 1; i <= n; i++) scanf("%I64d",&a[i]);for (int i = 1; i < n; i++) a[i] = a[i+1] - a[i],Modify(1,1,n-1,i,a[i]);cin >> m;while (m--){int l,r,x;scanf("%d%d%d",&l,&r,&x);if (n == 1){puts("1");continue;}if (l > 1) Modify(1,1,n-1,l-1,x);if (r < n) Modify(1,1,n-1,r,-x);printf("%d\n",Max[1] + 1);}return 0;}