Korean War: Bombing size and island

Question Description

In November 1951, the defend volunteers decided to bomb the size and the island in order to withstand the US military's frantic attack. Support Army trained to hit 90%! The size of the U.S. military and the island's facilities were destroyed. Now as most of the U.S. military to fight back to the volunteers, only a repairman, the repairman although driving a car, can arrive instantaneous, but repair or need time, if not timely repair, equipment will be scrapped. and equipment can only be repaired. What sort of repair order can I ask to keep more equipment?

Input

First line: is an integer n Next n rows: two integers per line t1,t2 It takes T1 minutes to repair the building, if not within T2 minutes. The building was scrapped when the repairs were completed.

Output

Output an integer s, which means that a maximum of s buildings can be repaired.

Input example

4 100 200 200 1300 1000 1250 2000 3200

Output example

3

Other Notes

Data range: n<15000

C Program:

#include <iostream>#include<cstring>#include<queue>#include<cstdio>#include<algorithm>using namespacestd;Const intn=150006;structBig_heap {inta[n<<1|1], tot; voidInitintN) { for(intI=1; I<= (n<<1|1); i++) a[i]=0; Tot=0; }    voidInsert (intval) {a[++tot]=Val;  for(intX=tot; X>1&& a[x]>a[x>>1]; x>>=1) Swap (a[x], a[x>>1]); }    voidUpdate (intval) {a[1]=Val;  for(intI=1, j=2; j<=tot; I=j, j<<=1) {            if((j|1) <=tot && a[j]<a[j|1]) j|=1; if(A[j]<a[i]) Break;        Swap (A[i], a[j]); }}} heap;structData {intT1, T2; BOOL operator< (ConstData &t)Const {        returnt2<t.t2; }} A[n];intN, ans, cur;intMain () { while(SCANF ("%d", &n)! =EOF) {         for(intI=0; i<n; i++) scanf ("%d%d", &a[i].t1, &a[i].t2); Sort (A, a+N); Cur=ans=0, Heap.init (n);  for(intI=0; i<n; i++) {            if(A[I].T1+CUR&LT;=A[I].T2) ans++, heap. Insert (A[I].T1), cur+=a[i].t1; Else {                if(!heap.tot)Continue; intVal=heap. a[1]; if(VAL&LT;=A[I].T1)Continue; Cur-=val-a[i].t1; Heap.            Update (A[I].T1); }} printf ("%d\n", ans); }    return 0;}

Korean War: Bombing size and island