题目大意：n个排成一列石头，其中有黑有白（1表示黑，0表示白），有两种操作：
（1）x=1,对相应区间的石头颜色取反。
（2）x=0，求相应区间内的最长连续的黑石石头的数目。
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1 #include <stdio.h> 2 #define lson l,m,rt<<1 3 #define rson m+1,r,rt<<1|1 4 #define maxn 100000 5 struct node 6 { 7 int llen1,llen0,rlen1,rlen0,maxlen1,maxlen0,col; 8 }setree[maxn<<2]; 9 int max(int a,int b) 10 { 11 return a>b?a:b; 12 } 13 int min(int a,int b) 14 { 15 return a<b?a:b; 16 } 17 void pushup(int rt,int len) 18 { 19 setree[rt].llen1=setree[rt<<1].llen1; 20 if(setree[rt<<1].llen1==len-len/2) 21 setree[rt].llen1+=setree[rt<<1|1].llen1; 22 23 setree[rt].rlen1=setree[rt<<1|1].rlen1; 24 if(setree[rt<<1|1].rlen1==len/2) 25 setree[rt].rlen1+=setree[rt<<1].rlen1; 26 27 setree[rt].maxlen1=max(setree[rt<<1].rlen1+setree[rt<<1|1].llen1,max(setree[rt<<1].maxlen1,setree[rt<<1|1].maxlen1)); 28 29 setree[rt].llen0=setree[rt<<1].llen0; 30 if(setree[rt<<1].llen0==len-len/2) 31 setree[rt].llen0+=setree[rt<<1|1].llen0; 32 33 setree[rt].rlen0=setree[rt<<1|1].rlen0; 34 if(setree[rt<<1|1].rlen0==len/2) 35 setree[rt].rlen0+=setree[rt<<1].rlen0; 36 37 setree[rt].maxlen0=max(setree[rt<<1].rlen0+setree[rt<<1|1].llen0,max(setree[rt<<1].maxlen0,setree[rt<<1|1].maxlen0)); 38 } 39 void pushdown(int rt) 40 { 41 if(setree[rt].col==2){ 42 int t; 43 44 if(setree[rt<<1].col==2) 45 setree[rt<<1].col=-1; 46 else 47 setree[rt<<1].col=2; 48 49 t=setree[rt<<1].llen1; 50 setree[rt<<1].llen1=setree[rt<<1].llen0; 51 setree[rt<<1].llen0=t; 52 53 t=setree[rt<<1].rlen1; 54 setree[rt<<1].rlen1=setree[rt<<1].rlen0; 55 setree[rt<<1].rlen0=t; 56 57 t=setree[rt<<1].maxlen1; 58 setree[rt<<1].maxlen1=setree[rt<<1].maxlen0; 59 setree[rt<<1].maxlen0=t; 60 61 if(setree[rt<<1|1].col==2) 62 setree[rt<<1|1].col=-1; 63 else 64 setree[rt<<1|1].col=2; 65 66 t=setree[rt<<1|1].llen1; 67 setree[rt<<1|1].llen1=setree[rt<<1|1].llen0; 68 setree[rt<<1|1].llen0=t; 69 70 t=setree[rt<<1|1].rlen1; 71 setree[rt<<1|1].rlen1=setree[rt<<1|1].rlen0; 72 setree[rt<<1|1].rlen0=t; 73 74 t=setree[rt<<1|1].maxlen1; 75 setree[rt<<1|1].maxlen1=setree[rt<<1|1].maxlen0; 76 setree[rt<<1|1].maxlen0=t; 77 78 setree[rt].col=-1; 79 } 80 } 81 void build(int l,int r,int rt) 82 { 83 if(l==r){ 84 scanf("%d",&setree[rt].col); 85 setree[rt].llen1=setree[rt].rlen1=setree[rt].maxlen1=setree[rt].col?1:0; 86 setree[rt].llen0=setree[rt].rlen0=setree[rt].maxlen0=setree[rt].col?0:1; 87 return; 88 } 89 setree[rt].col=-1; 90 int m=(l+r)>>1; 91 build(lson); 92 build(rson); 93 pushup(rt,r-l+1); 94 } 95 void update(int l,int r,int rt,int L,int R) 96 { 97 int t; 98 if(L<=l&&r<=R){ 99 if(setree[rt].col==2) 100 setree[rt].col=-1; 101 else 102 setree[rt].col=2; 103 t=setree[rt].llen1; 104 setree[rt].llen1=setree[rt].llen0; 105 setree[rt].llen0=t; 106 107 t=setree[rt].rlen1; 108 setree[rt].rlen1=setree[rt].rlen0; 109 setree[rt].rlen0=t; 110 111 t=setree[rt].maxlen1; 112 setree[rt].maxlen1=setree[rt].maxlen0; 113 setree[rt].maxlen0=t; 114 return; 115 } 116 pushdown(rt); 117 int m=(l+r)>>1; 118 if(L<=m) 119 update(lson,L,R); 120 if(R>m) 121 update(rson,L,R); 122 pushup(rt,r-l+1); 123 } 124 int query(int l,int r,int rt,int L,int R) 125 { 126 if(L<=l&&r<=R) 127 return setree[rt].maxlen1; 128 pushdown(rt); 129 int m=(l+r)>>1; 130 if(R<=m) 131 return query(lson,L,R); 132 else if(L>m) 133 return query(rson,L,R); 134 else{ 135 int temp=max(query(lson,L,m),query(rson,m+1,R)); 136 temp=max(min(m-L+1,setree[rt<<1].rlen1)+min(R-m,setree[rt<<1|1].llen1),temp); 137 return temp; 138 } 139 } 140 int main() 141 { 142 int n; 143 while(~scanf("%d",&n)){ 144 build(1,n,1); 145 int op; 146 scanf("%d",&op); 147 while(op--){ 148 int a,b,c; 149 scanf("%d%d%d",&a,&b,&c); 150 if(a==1) 151 update(1,n,1,b,c); 152 else 153 printf("%d\n",query(1,n,1,b,c)); 154 } 155 } 156 return 0; 157 }
