Poj 2828 buy tickets

From the back to the front, you can find the position where the front is exactly set to k positions.

 

//============================================================================// Name        : F.cpp// Author      : L_Ecry// Version     :// Copyright   : Your copyright notice// Description : Hello World in C++, Ansi-style//============================================================================#include<cstdio>#include<iostream>#include<cstring>#include<algorithm>#include<cmath>#define N 200050using namespace std;int sum[N * 4];void build(int l, int r, int i) {    sum[i] = r - l + 1;    if (l != r) {        int mid = (l + r) >> 1;        build(l, mid, i << 1);        build(mid + 1, r, i << 1 | 1);    }}int update(int l, int r, int va, int i) {    sum[i]--;    if (l == r) {        return l;    }    int mid = (l + r) >> 1;    if (sum[i << 1] > va)        return update(l, mid, va, (i << 1));    else        return update(mid + 1, r, va - sum[i << 1], (i << 1 | 1));}int n;int ans[N];int x[N], y[N];int main() {    while (scanf("%d", &n) != EOF) {        build(1, n, 1);        for (int i = 0; i < n; ++i)            scanf("%d%d", &x[i], &y[i]);        for (int i = n-1; i >-1; --i) {            int tmp = update(1, n, x[i], 1);            ans[tmp] = y[i];        }        for (int i = 1; i < n; ++i) {            printf("%d ", ans[i]);        }        printf("%d\n",ans[n]);    }    return 0;}