HDU 4339 (line segment tree Character Mark)

The two strings S1 and S2 are given several queries.

Query operation:

1 a B c: replace character B of character a with character C

2. A queries the number of S1 [k] = S2 [k] starting from the character. For example, aaa aab queries 2 0 and the result is 2.

Idea: the leaf value of a line segment tree is set to I + 1 with different positions, initially Len + 1. the minimum value of the interval is not queried, that is, the first position of the Line Segment tree;

#include<iostream>#include<cstring>#include<cstdlib>#include<cstdio>#include<algorithm>#define N 1000010#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1using namespace std;char s[2][N];int val[N<<2];int INF;void pushup(int rt){    val[rt]=min(val[rt<<1],val[rt<<1|1]);}void build(int l,int r,int rt){    val[rt]=INF;    if(l==r)        return;    int m=(l+r)>>1;    build(lson);    build(rson);}void update(int p,int v,int l,int r,int rt){    if(l==r)    {        val[rt]=v;        return;    }    int m=(l+r)>>1;    if(p<=m) update(p,v,lson);    else update(p,v,rson);    pushup(rt);}int query(int L,int R,int l,int r,int rt){    //cout<<"---"<<endl;    int ans=INF;    if(L<=l&&r<=R)    {        return val[rt];    }    int m=(l+r)>>1;    if(L<=m) ans=min(ans,query(L,R,lson));    if(R>m) ans=min(ans,query(L,R,rson));    return ans;}int main(){    int T;    scanf("%d",&T);    for(int cas=1;cas<=T;cas++)    {        scanf("%s%s",s[0],s[1]);        int len=min(strlen(s[0]),strlen(s[1]));        INF=len+1;        build(1,len,1);        for(int i=0;i<len;i++)        {            if(s[0][i]==s[1][i]) update(i+1,INF,1,len,1);            else update(i+1,i+1,1,len,1);        }        int n,op;        int a,b;        char c[2];        scanf("%d",&n);        printf("Case %d:\n",cas);        for(int i=0;i<n;i++)        {            scanf("%d",&op);            if(op==2)            {                scanf("%d",&a);                if(a>=len)                    printf("0\n");                else                    printf("%d\n",query(a+1,len,1,len,1)-a-1);            }            else            {                scanf("%d%d%s",&b,&a,c);                if(a>=len)                    continue;                b--;                if(s[b][a]==s[b^1][a]&&s[b^1][a]!=c[0]) update(a+1,a+1,1,len,1);                if(s[b][a]!=s[b^1][a]&&s[b^1][a]==c[0]) update(a+1,INF,1,len,1);                s[b][a]=c[0];            }        }    }    return 0;}

HDU 4339 (line segment tree Character Mark)