#include<stdio.h>
typedef long long lld;
const lld mod = 1000000007;
lld ex(lld a, lld b){
lld gop=1;
for(; b; b>>=1){
if(b&1) gop=gop*a%mod;
a=a*a%mod;
}
return gop;
}
lld r, h, rh, dy1[5050][5050], dy2[5050][5050];
int N, A, B, x, y, xys[5050][2], xyc;
bool chk[5050][5050];
char st[5050];
void make_route(int s){
int pv=0;
for(int i=s; i<N; i++){
if(st[i]=='R'){
if(pv==-1) xys[xyc][0]=x, xys[xyc][1]=y, xyc++;
else if(x) chk[x-1][y]=1;
y++, pv=1;
}
else{
if(pv==1) chk[x][y]=1;
chk[x][y+1]=1;
x++, pv=-1;
}
}
chk[x][y+1]=1;
}
int main(){
scanf("%d%lld%lld", &N, &r, &h), rh=ex(r+h,mod-2);
r=r*rh%mod, h=h*rh%mod;
scanf("\n%s", st);
scanf("%d%d", &A, &B);
while(N){
if(st[N-1] != 'R') break;
N--, A--;
}
st[N]=0;
for(int i=0; i<=N; i++){
if(i==N || st[i] != 'H'){
make_route(i);
N -= i;
break;
}
B--;
}
if(A<0 || B<0){ puts("0"); return 0; }
if(N==0){
puts(A==0&&B==0 ? "1" : "0");
return 0;
}
dy1[B][0]=1;
for(int i=0; i<=x; i++){
for(int j=1; j<=y; j++){
if(chk[i][j]) continue;
dy1[i][j] += dy1[i][j-1]*r;
if(i) dy1[i][j] += dy1[i-1][j]*h;
dy1[i][j] %= mod;
}
}
dy2[x][y-A]=1;
for(int i=x-1; i>=0; i--){
for(int j=y; j>=0; j--){
if(chk[i][j]) continue;
dy2[i][j] += dy2[i][j+1]*r;
dy2[i][j] += dy2[i+1][j]*h;
dy2[i][j] %= mod;
}
}
if(A==0){ printf("%lld\n", dy1[x][y]); return 0; }
if(B==0){ printf("%lld\n", dy2[0][0]); return 0; }
lld sum=0;
for(int i=0; i<xyc; i++){
int r=xys[i][0], c=xys[i][1];
sum += dy1[r][c]*dy2[r][c];
sum %= mod;
}
printf("%lld\n", sum);
return 0;
}
Compilation message
dstorv.c:17:1: error: unknown type name 'bool'; did you mean '_Bool'?
bool chk[5050][5050];
^~~~
_Bool
dstorv.c: In function 'main':
dstorv.c:38:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d%lld%lld", &N, &r, &h), rh=ex(r+h,mod-2);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dstorv.c:40:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
scanf("\n%s", st);
^~~~~~~~~~~~~~~~~
dstorv.c:41:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d%d", &A, &B);
^~~~~~~~~~~~~~~~~~~~~
