hdu 1166 線段樹/樹狀數組

http://acm.hdu.edu.cn/showproblem.php?pid=1166

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本人做的第一道線段樹的題，紀念一下吧

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/**********************************Accepted 1166 46MS 2476K 1572 B C++**********************************/#include<iostream>using namespace std;struct node{int left,right,mid;int num;//該結點士兵數}a[150000];//通常3*n的空間就okint st[50010],sum;void creat(int s,int t,int step)//建樹{a[step].left=s;a[step].right=t;a[step].mid=(s+t)/2;if(s==t){a[step].num=st[t];return ;}creat(s,a[step].mid,2*step);creat(a[step].mid+1,t,2*step+1);a[step].num=a[2*step].num+a[2*step+1].num;}void add(int ans1,int ans2,int step)//Sub & Add函數{a[step].num+=ans2;//為啥要放在這裡？因為每棵子樹都是內含項目關聯性，看看線段樹就知道了，【這裡每個節點都儲存了子樹士兵的和】if(a[step].left==a[step].right){return ;}if(ans1<=a[step].mid)add(ans1,ans2,2*step);elseadd(ans1,ans2,2*step+1);}void find(int s,int t,int step){if(s==a[step].left && t==a[step].right){sum+=a[step].num;return ;}//詢問時遇到匹配的線段就return！if(t<=a[step].mid)find(s,t,2*step);elseif(s>a[step].mid)find(s,t,2*step+1);else{find(s,a[step].mid,2*step);find(a[step].mid+1,t,2*step+1);}}int main(){freopen("a.txt","r",stdin);int ca;while(scanf("%d",&ca)!=EOF){int nca;for(nca=1;nca<=ca;nca++){printf("Case %d:\n",nca);int n;scanf("%d",&n);int i;for(i=1;i<=n;i++)scanf("%d",&st[i]);creat(1,n,1);char str[10];while(scanf("%s",str)){if(str[0]=='E')break;int ans1,ans2;scanf("%d%d",&ans1,&ans2);if(str[0]=='A')add(ans1,ans2,1);if(str[0]=='S')//減的時候可以取負再調用add函數{ans2=-ans2;add(ans1,ans2,1);}if(str[0]=='Q'){sum=0;find(ans1,ans2,1);printf("%d\n",sum);}}}}return 0;}

 

貼一個樹狀數組的

#include <iostream>using namespace std;int tree[50005];int n;int Lowbit(int k){    return k&(-k);    //return k&(k^(k-1));}int Sum(int a){    int result = 0;    while(a != 0)    {        result += tree[a];        a -= Lowbit(a);    }    return result;}void Modify(int a,int c,int n){    while(a<=n)    {        tree[a] += c;        a +=Lowbit(a);    }}int main(){freopen("a.txt","r",stdin);    int i,j,k;    int Tcase=0;    int Case;    char ch[10];    scanf("%d",&Case);    while(Case--)    {        printf("Case %d:\n",++Tcase);        memset(tree,0,sizeof(tree));        scanf("%d",&n);        for(i=1;i<=n;i++)        {            scanf("%d",&k);            Modify(i,k,n);        }        while(1)        {            scanf("%s",&ch);            if(ch[0]=='E')break;            scanf("%d%d",&i,&j);            if(ch[0]=='Q')                printf("%d\n",Sum(j)-Sum(i-1));            else if(ch[0]=='A')                Modify(i,j,n);            else if(ch[0]=='S')                Modify(i,-j,n);        }    }    return 0;}