分块

　　bzoj2002 弹飞绵羊

这种写法不太好，容易错

#include <iostream>
#include <string.h>
#include <cstdio>
#include <queue>
#include <vector>
#include <cstring>
#include <algorithm>
#include <math.h>

#define SIGMA_SIZE 26
#pragma warning ( disable : 4996 )

using namespace std;
typedef long long LL;
//typedef unsigned long long uLL;

inline LL LMax(LL a,LL b)    { return a>b?a:b; }
inline LL LMin(LL a,LL b)    { return a>b?b:a; }
inline int Max(int a,int b) { return a>b?a:b; }
inline int Min(int a,int b) { return a>b?b:a; }
inline int gcd( int a, int b ) { return b==0?a:gcd(b,a%b); }
inline int lcm( int a, int b ) { return a/gcd(a,b)*b; }  //a*b = gcd*lcm
const long long INF = 0x3f3f3f3f3f3f3f3f;
const int inf  = 0x3f3f3f3f;
const int mod  = 7;
const int maxk = 5005;
const int maxn = 2e5+5;

int n, m;
int ki[maxn];
int pos[maxn], times[maxn];

int main()
{
    cin >> n;
    for ( int i = 0; i < n; i++ )
        scanf("%d", &ki[i]);
    cin >> m;

    int block = sqrt(n);

    for ( int i = n - 1; i >= 0; i-- )
    {
        int tmp = i+ki[i];
        if ( tmp >= n )
            { pos[i] = -1; times[i] = 1; }
        else if ( tmp >= (i/block+1)*block )
            { pos[i] = tmp; times[i] = 1; }
        else
            { pos[i] = pos[tmp]; times[i] = times[tmp]+1; }
    }

    int x, y, k;
    for ( int j = 0; j < m; j++ )
    {
        scanf("%d", &x);
        if ( x == 2 )
        {
            scanf( "%d %d", &y, &k );
            ki[y] = k;

            for ( int i = y; i >= (y / block)*block; i-- )
            {
                int tmp = i+ki[i];
                if ( tmp >= n )
                    { pos[i] = -1; times[i] = 1; }
                else if ( tmp >= (i/block+1)*block )
                    { pos[i] = tmp; times[i] = 1; }
                else
                    { pos[i] = pos[tmp]; times[i] = times[tmp] + 1; }
            }
        }
        else
        {
            scanf("%d", &y);
            int ans = 0;
            for ( int i = y; i+1; i = pos[i] )
                ans += times[i]; 
            printf( "%d
", ans );
        }
    }

    return 0;
}