hdu 5357 2015-08-10 22:52 7人阅读 评论(0) 收藏
括号匹配,栈
开始感觉题意很奇怪,表示这道题不会做。。。然而看了题解,原来并不是太难啊~!
我太弱了,还是直接贴代码吧。。。
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <string>
#include <map>
#include <vector>
#include <stack>
#include <queue>
#include <utility>
#include <iostream>
#include <algorithm>
template<class Num>void read(Num &x)
{
char c; int flag = 1;
while((c = getchar()) < '0' || c > '9')
if(c == '-') flag *= -1;
x = c - '0';
while((c = getchar()) >= '0' && c <= '9')
x = (x<<3) + (x<<1) + (c-'0');
x *= flag;
return;
}
template<class Num>void write(Num x)
{
if(x < 0) putchar('-'), x = -x;
static char s[20];int sl = 0;
while(x) s[sl++] = x%10 + '0',x /= 10;
if(!sl) {putchar('0');return;}
while(sl) putchar(s[--sl]);
}
const int maxn = 1e6 + 50, Mod = 1e9+7;
char str[maxn];
int T, n, a[maxn], b[maxn];
int pre[maxn], match[maxn];
long long ans[maxn];
int stack[maxn], top;
void prework()
{
top = 0;
for(int i = 1; i <= n; i++)
{
match[i] = pre[i] = 0;
if(str[i] == '(')
stack[++top] = i;
else
{
if(top)
{
match[stack[top]] = i;
match[i] = stack[top];
if(top > 1) pre[match[i]] = stack[top - 1];
stack[top--] = 0;
}
}
}
}
void solve()
{
a[0] = b[n + 1] = ans[0] = 0;
for(int i = 1; i <= n; i++)
a[i] = (str[i] == ')' && match[i])?(a[match[i] - 1] + 1):0;
for(int i = n; i >= 1; i--)
b[i] = (str[i] == '(' && match[i])?(b[i] = b[match[i] + 1] + 1):0;
for(int i = 1; i <= n; i++)
ans[i] = (str[i] == '(')?(ans[pre[i]] + ((long long)b[i]*a[match[i]] % Mod) % Mod):ans[match[i]];
}
long long calcu()
{
long long tot = 0;
for(int i = 1; i <= n; i++)
tot = tot + ans[i]*i % Mod;
return tot;
}
int main()
{
#ifndef ONLINE_JUDGE
freopen("5357.in","r",stdin);
freopen("5357.out","w",stdout);
#endif
read(T);
while(T--)
{
scanf("%s", str + 1);
n = strlen(str + 1);
prework(), solve();
write(calcu()), puts("");
}
#ifndef ONLINE_JUDGE
fclose(stdin);
fclose(stdout);
#endif
return 0;
}
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