【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+;
 char s[maxn];
 node_t nd[maxn<<];
 int L, R;

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

 inline void PushDown(int rt) {
     if (nd[rt].f) {
         int lb = rt<<;
         int rb = lb|;
         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 + ;
     if (l == r) {
         nd[rt].ln = (s[l] == '');
         return ;
     }

     int mid = (l + r) >> ;
     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) >> ;
     int ret;

     if (nd[rt<<].ln == nd[rt<<].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) >> ;

     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+);
         Build(, n, );
         if (nd[].tot == nd[].ln) {
             puts("");
             continue;
         }
         if (l == ) {
             puts("-1");
             continue;
         }

         ans = ;
         while () {
             ++ans;
             k = Query(, n, );
             L = k;
             R = L + l - ;
             #ifndef ONLINE_JUDGE
                 // printf("k = %d\n", k);
             #endif
             if (R > n) {
                 ans = -;
                 break;
             }
             Update(, n, );
             if (nd[].tot == nd[].ln)
                 break;
         }
         printf("%d\n", ans);
     }

     #ifndef ONLINE_JUDGE
         printf("time = %d.\n", (int)clock());
     #endif

     return ;
 }