Woj 1575-signal Generators Monotone Queue optimization DP + blind

Poke here: 1575

Test instructions: N signal transmitters are arranged on a straight line, and each transmitter activated will cause all transmitters within the affected range to be activated. Ask what is the maximum number of transmitters activated after activating any one of the transmitters.

Official problem: May exist in the case of the ring, consider the sort by coordinates I < J < K,j activated K, and then k again activate I. However, this can be translated into a program that directly activates K. So no impact. You can then use DP solution. Dp[i] = max (Dp[j] + 1), Position[j] + r[i] >= position[i], with monotonic queue optimization time complexity is O (n). To the left and right respectively DP again. The maximum value of the last statistic answer.

is also at that time WHU invitational scene did not make out a problem. Back to look at the puzzle, the sense of the puzzle does not take into account all the situation, such as the first signal transmitter on the left side of the two non-affected signal emitter group, and the impact of the first signal transmitter can cover the two lump, at this time if the direct use of monotone queue optimization, You can only select two lump in the signal emitter of the largest lump as a precursor to the formation of the optimal solution (in fact, should both be selected)

I couldn't solve the problem, so I started messing around ... WA a few rounds, the last time before the feeling there is no AC possibility, but the blind code to turn up after the AC got it ...!!!

My practice is: as far as possible to extend the scope of the signal transmitter, the extension of the standard is other completely covered by the signal transmitter of the influence of the range of the signal transmitter (the impact range), so that the left side has two non-affected signal emitter group together as a lump, dp[I] is good to do

1#include"bits/stdc++.h"2 using namespacestd;3 //Dp[i] = max (Dp[j] + 1);4 intN;5 Long Longpos[1000010];6 intr[1000010], r_1[1000010], r_2[1000010];7 intdp_1[1000010], dp_2[1000010];8 9 structTen { One     Long Longindex; A     intvalue; -}q[1000010], TMP; - intfront, rear; the  - intMain () - { -      while(SCANF ("%d", &n)! =EOF) { +         //Initialize -memset (Dp_1,0,sizeof(int) * (N +1)); +memset (dp_2,0,sizeof(int) * (N +1)); A         inti, X; at         //input -         intMostlongradius =0; -          for(i =1; I <= N; ++i) { -scanf"%d%d", &x, &r[i]); -Mostlongradius-=x; -R_2[i] =Max (R[i], Mostlongradius); inMostlongradius =R_2[i]; -Pos[i] = pos[i-1] +x; to         } +Mostlongradius =R[n]; -          for(i = N-1; I >=1; --i) { theMostlongradius-= (Pos[i +1] -pos[i]); *R_1[i] =Max (R[i], Mostlongradius); $Mostlongradius =R_1[i];Panax Notoginseng         } -         //preprocessing a state in which a monotonic queue optimization is not possible because there are no precursors thedp_1[1] =0; +         //start with a pre-active DP AFront = Rear =1; the          for(i =2; I <= N; ++i) { +Tmp.value = Dp_1[i-1]; -Tmp.index = Pos[i-1]; $              for(; Front < rear && Tmp.value > Q[rear-1].value; --rear); $q[rear++] =tmp; -              for(; Front < rear && Pos[i]-tmp.index > R_1[i]; + +front); -             if(Front! =rear) { theDp_1[i] = Q[front].value +1; -             }Wuyi             Else { theDp_1[i] =0; -             } Wu         } -         intres =0; About         //preprocessing a state in which a monotonic queue optimization is not possible because there are no precursors $Dp_2[n] =0; -         //start with a pre-active DP -Front = Rear =1; -          for(i = N-1; I >=1; --i) { ATmp.value = Dp_2[i +1]; +Tmp.index = Pos[i +1]; the              for(; Front < rear && Tmp.value > Q[rear-1].value; --rear); -q[rear++] =tmp; $              for(; Front < rear && tmp.index-pos[i] > R_2[i]; + +front); the             if(Front! =rear) { theDp_2[i] = Q[front].value +1; the             } the             Else { -Dp_2[i] =0; in             } theres = max (res, dp_1[i] + dp_2[i] +1); the         } Aboutprintf"%d\n", res); the     } the}

Woj 1575-signal Generators Monotone Queue optimization DP + blind