Sigma 2012 Codility Programming Certificate Solution

Stone wall.js

/* http://blog.codility.com/2012/06/sigma-2012-codility-programming.html */

function stone_wall ( H ) {
    var blocks = 0, stack = [], m, stack_length = 0;
    
    for(m in H) {        
        // I use stack to remember all previous skyline levels
        while(stack_length > 0 && stack[stack_length - 1] > H[m]) {
            stack_length -= 1;
            blocks += 1;
        }        
        if(stack_length === 0 || stack[stack_length - 1] < H[m]) {
            stack[stack_length] = H[m];
            stack_length += 1;
        } 
    }
    return blocks + stack_length;
}