【HDOJ】3275 Light

这就是个简单线段树+延迟标记。因为对bool使用了~而不是！，wa了一下午找不到原因。

/* 3275 */
#include <iostream>
#include <sstream>
#include <string>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <deque>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <climits>
#include <cctype>
#include <cassert>
#include <functional>
#include <iterator>
#include <iomanip>
using namespace std;
//#pragma comment(linker,"/STACK:102400000,1024000")

#define sti                set<int>
#define stpii            set<pair<int, int> >
#define mpii            map<int,int>
#define vi                vector<int>
#define pii                pair<int,int>
#define vpii            vector<pair<int,int> >
#define rep(i, a, n)     for (int i=a;i<n;++i)
#define per(i, a, n)     for (int i=n-1;i>=a;--i)
#define clr                clear
#define pb                 push_back
#define mp                 make_pair
#define fir                first
#define sec                second
#define all(x)             (x).begin(),(x).end()
#define SZ(x)             ((int)(x).size())
#define lson            l, mid, rt<<1
#define rson            mid+1, r, rt<<1|1

typedef struct {
    bool f;
    int ln, tot;
} node_t;

const int maxn = 1e5+5;
char s[maxn];
node_t nd[maxn<<2];
int L, R;

inline void PushUp(int rt) {
    nd[rt].ln = nd[rt<<1].ln + nd[rt<<1|1].ln;
}

inline void PushDown(int rt) {
    if (nd[rt].f) {
        int lb = rt<<1;
        int rb = lb|1;
        nd[lb].f = !nd[lb].f;
        nd[lb].ln = nd[lb].tot - nd[lb].ln;
        nd[rb].f = !nd[rb].f;
        nd[rb].ln = nd[rb].tot - nd[rb].ln;
        nd[rt].f = false;
    }
}

void Build(int l, int r, int rt) {
    nd[rt].f = false;
    nd[rt].tot = r - l + 1;
    if (l == r) {
        nd[rt].ln = (s[l] == '1');
        return ;
    }
    
    int mid = (l + r) >> 1;
    Build(lson);
    Build(rson);
    
    PushUp(rt);
}

int Query(int l, int r, int rt) {
    if (l == r)
        return l;
    
    PushDown(rt);
    int mid = (l + r) >> 1;
    int ret;
    
    if (nd[rt<<1].ln == nd[rt<<1].tot)
        ret = Query(rson);
    else
        ret = Query(lson);
    PushUp(rt);
    
    return ret;
}

void Update(int l, int r, int rt) {
    if (L<=l && R>=r) {
        nd[rt].f = !nd[rt].f;
        nd[rt].ln = nd[rt].tot - nd[rt].ln;
        return ;
    }
    
    PushDown(rt);
    int mid = (l + r) >> 1;
    
    if (R <= mid) {
        Update(lson);
    } else if (L > mid) {
        Update(rson);
    } else {
        Update(lson);
        Update(rson);
    }
    
    PushUp(rt);
}

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    int n, l;
    int ans, k;
    
    while (scanf("%d %d",&n,&l)!=EOF && (n||l)) {
        scanf("%s", s+1);
        Build(1, n, 1);
        if (nd[1].tot == nd[1].ln) {
            puts("0");
            continue;
        }
        if (l == 0) {
            puts("-1");
            continue;
        }
        
        ans = 0;
        while (1) {
            ++ans;
            k = Query(1, n, 1);
            L = k;
            R = L + l - 1;
            #ifndef ONLINE_JUDGE
                // printf("k = %d\n", k);
            #endif
            if (R > n) {
                ans = -1;
                break;
            }
            Update(1, n, 1);
            if (nd[1].tot == nd[1].ln)
                break;
        }
        printf("%d\n", ans);
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.\n", (int)clock());
    #endif
    
    return 0;
}