题解 | #矩阵乘法计算量估算#

#include <stdio.h>
#include <string.h>

int main() {
    int n;
    scanf("%d",&n);
    int fan[15][2];
    for (int i = 0; i<n; i++) {
        scanf("%d %d",&fan[i][0],&fan[i][1]);
    }

    char x[100];
    scanf("%s",x);
    int len = strlen(x);

    int a[100] = {0};
    int b[100] = {0};
    int top[100] = {0};
    int sum = 0;
    int m = 0;
    int g = 0;
    for (int i = 0; i<len; i++) {
        if (x[i] == '(') {
            top[m++]=i;          
        }
        if (x[i] >= 'A' && x[i] <= 'Z') {
            int temp = x[i] - 'A';
            a[g] = fan[temp][0];
            b[g] = fan[temp][1];
            g++;
        }
        if (x[i] == ')') {
            //for (int j =i-2; j>=top[m-1]+1; j--) {        无法排除空位部分计算会失败
                sum += a[g-1]*b[g-1]*a[g-2];
                b[g-2] = b[g-1];
                g--;
              //  g = b[j+1];
                //b[j+1] = 0;
               // printf("%d\n",sum);
               // printf("%d\n",i);
               // printf("%d\n",top[m-1]+1);
            
            //b[top[m-1]+1] = 0;
           // m--;
        }
    }

    printf("%d",sum);
    return 0;
}