poj 2828 Buy Tickets

#include<cmath>
#include<vector>
#include<string>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
typedef long long LL;
const int M = 200009;
int ans[M], pos[M], val[M];
struct SegNode {
int left, right, delay;
void init(int a, int b)
{
delay = b - a + 1;
left = a;
right = b;
}
} seg[M << 2];
int L(int n)
{
return n << 1;
}
int R(int n)
{
return n << 1 | 1;
}
void build(int N, int a, int b)
{
seg
.init(a, b);
if(a == b) { return ; }
int mid = (a + b) >> 1;
build(L(N), a, mid);
build(R(N), mid + 1, b);
}

int update(int N, int id)
{
seg
.delay--;
if(seg
.left == seg
.right) { return seg
.left; }
if(seg[L(N)].delay >= id) { update(L(N), id); }
else { return update(R(N), id - seg[L(N)].delay); }
}

int main()
{
int n, sum, i, m;
while(~scanf("%d", &n)) {
for(i=0; i<n; ++i) {
scanf("%d%d", &pos[i], &val[i]);
}
build(1, 1, n);
for(i=n-1; i>=0; --i) {
ans[update(1, pos[i] + 1)] = val[i];
}
for(i=1; i<=n; ++i) {
printf("%d%c", ans[i], i == n ? '\n' : ' ');
}
}
return 0;
}